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MLB Power Rankings

Looking at the various MLB power rankings that websites do got me interested in how they come up with their lists. It seems pretty arbitrary, so I decided to come up with somehing a little less random. It's kind of like ESPN's Relative Power Index, but my formula is quite different. The idea is that the number assigned to each team will represent a projected winning percentage so that the rankings also project the total number of wins for the season.

Star-divide

I'll keep this simple. The four factors I use to rank each team are 50% current record, 25% strength of schedule (from ESPN), 15% run differential, and 10% recent performance. If you guys have any ideas about how I should adjust the formula, let me know. It wouldn't be hard for me to post these on a semi-regular basis through the rest of the season if there's interest. Let me know what you think.

Team

Power

Wins

LAD

0.608

98.4

TOR

0.605

98.1

MIL

0.583

94.4

BOS

0.577

93.4

NYM

0.57

92.4

TEX

0.568

92.1

CIN

0.565

91.6

CHC

0.561

90.8

STL

0.539

87.3

LAA

0.539

87.3

DET

0.538

87.2

SF

0.537

86.9

KC

0.529

85.7

PHI

0.512

83

ATL

0.501

81.1

TB

0.489

79.2

MIN

0.489

79.1

FLA

0.481

77.9

HOU

0.473

76.7

CHW

0.454

73.6

NYY

0.453

73.4

BAL

0.453

73.4

COL

0.452

73.3

SEA

0.45

72.8

OAK

0.446

72.3

PIT

0.428

69.3

CLE

0.414

67.1

WAS

0.405

65.7

ARI

0.393

63.7

SD

0.367

64.3

3 recs  |  Comment 26 comments

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Clearly something is off on these rankings

if Washington is not the worst team….

I think you need to take into account strength of remaining schedule?

And I don’t know why recent performance should matter in projecting wins over the long haul

by tiimbitz4786 on May 14, 2009 1:46 PM EDT reply actions   0 recs

For a weekly power rankings system

it makes sense to project wins w/ recent performance. But it shouldn’t be given very much weight, which it isn’t. 10% is about right for current performance. If your team is playing hot and winning right now, those wins are going towards your final total.

Patiently awaiting the day Colby Rasmus does this: .275/.381/.551/.932, 29HR, in St. Louis...and I'm wanting an Allen Craig call-up!

by RunninRedbird on May 14, 2009 2:15 PM EDT up reply actions   0 recs

there is something wrong

this formula suggests that there are 3 NL central teams better than the Cards. It can’t be right!

by cdb on May 14, 2009 2:18 PM EDT up reply actions   0 recs

aaaaargh i HATE the "backspace is back" function in mozilla

i just lost 45 minutes worth of response, and I don’t have the energy to type it again. Anyone know a way to make that “feature” go away?

Anyway, I suggested a way to try to remove luck over games played so far from the “future wins” calculations by looking at current record*strength of schedule (if you think SoS matters) + (future wins determined using something like FIP and baseruns). Or take it a step further and derive a FIP adjusted to account for team defensive skill using DER (someone has probably already done this).

Your formula attempts to do this by looking at run differential, but RS and RA are both functions of luck…

Also my gut feel is that “recent play” means diddly, but I could easily be totally wrong about that. If anything, recent play might be a negative, since there’s a decent chance it means your ace just pitched and won’t again for 4 days.

- "I went at it and didn’t slow down, so it kind of bounced off me." -Lil' Dunc

by SleepyCA on May 14, 2009 11:03 PM EDT reply actions   0 recs

also

want to reiterate that the only thing “current record” should be used for is “wins so far”. Having gone 10-0 to start a season doesn’t make a team any more likely to win a game in september, but it makes that team more likely to win “x” games because those wins are on the books and don’t HAVE to be won in september. Their record from day “x” should be based on the true talent of the team (and the true talent of the opposition, though I’d guess that averages out over a couple of series).

The question is just “how do we estimate the true talent of the team going forward, and add it to what they’ve done so far”.

- "I went at it and didn’t slow down, so it kind of bounced off me." -Lil' Dunc

by SleepyCA on May 14, 2009 11:07 PM EDT up reply actions   0 recs

Current record seems to me to be the most direct way of predicting how a team will perform

If I wanted to just come up wit a rough guess as to how a team will finish the season, I’d probably just go and multiply their current winning percentage by 162.

How they’ve done is probably a pretty decent first guess as to how they will do.

They say that it's never too late, but you don't get any younger...

by Valatan on May 18, 2009 10:30 AM EDT up reply actions   0 recs

Are you joking?

St. Louis Cardinals... defying win expectancy since 2008

by vivaelpujols on May 18, 2009 12:08 PM EDT up reply actions   0 recs

Everything is a guess

Two months in, to first order, current record is as good a predictor as anything. And it is simple and based on actual raw data.

They say that it's never too late, but you don't get any younger...

by Valatan on May 18, 2009 3:05 PM EDT up reply actions   0 recs

That's not true at all

One guess is a lot better than another. Projection systems try to estimate the teams true talent level based on years of data for each individual player. That is much more thorough assessment of a teams true talent level (and more accurate) than even a full seasons worth of wins is.

St. Louis Cardinals... defying win expectancy since 2008

by vivaelpujols on May 18, 2009 3:35 PM EDT up reply actions   0 recs

A projection of the thing you're trying to measure

is more accurate than the thing itself?

I might be able to buy that it’s more precise, but it certainly not more accurate.

And note that I said to first order.

They say that it's never too late, but you don't get any younger...

by Valatan on May 18, 2009 3:42 PM EDT up reply actions   0 recs

There are a couple ways to do that

1) Using Bayesian inference, you can take their preseason projected record as their prior and weigh it with what they have already done. That would allow you to come up with a new xW% for the team. Then exptrapolate that to the remaining games that a team has on it’s schedule, and add that to the wins that the team already has. That’s the most scientific way to do it, and would work well in a spreadsheet.

2) You could update the prior winning percentage based on what’s happened so far manually. By that I mean you look at how certain players have performed/underperformed, injuries, promotions/demotions, etc. The problem with that is it is somewhat subjective and may lead you to overly optimistic/pessimistic results. Also, it would be hard to do for other teams, as you wouldn’t be as familiar with them as you would be with the Cards.

St. Louis Cardinals... defying win expectancy since 2008

by vivaelpujols on May 18, 2009 12:13 PM EDT up reply actions   0 recs

Well, #2 is wayyyy to subjective to go along with the idea of the data based rankings.

  1. could work, but then you have to decide what preseason projection to use. That’s ignoring the fact that those projections don’t really mean much. A team that is underrated before the season and does well will always be ranked low on the power rankings.

The Godfather himself has decided to grace us with his presence. This is his damn house. He sleeps 20 feet away.

by thegodfather on May 18, 2009 2:48 PM EDT up reply actions   0 recs

Actually

You should read this article. It turns out that preseason projections are actually a better true talent level estimate (base on RMSE) than the teams record is.

St. Louis Cardinals... defying win expectancy since 2008

by vivaelpujols on May 18, 2009 3:33 PM EDT up reply actions   0 recs

I'm confused

The whole point is to estimate the team’s win total and rank them in terms of it. I don’t care how talented the team is if they aren’t winning.

The Godfather himself has decided to grace us with his presence. This is his damn house. He sleeps 20 feet away.

by thegodfather on May 18, 2009 5:03 PM EDT up reply actions   0 recs

oh

St. Louis Cardinals... defying win expectancy since 2008

by vivaelpujols on May 18, 2009 7:59 PM EDT up reply actions   0 recs

I actually think

the problem is that too many online power rankings take in recent performance. A bad week should definitely have an impact, but too much of the time it just slaughters a team’s power rankings.

On with the (good) youth movement!

by aet15 on May 15, 2009 2:08 AM EDT reply actions   0 recs

i think that's the purpose of power rankings.

if they don’t change week-by-week, why are readers going to read it? “you don’t say, the red sox are STILL the best team in baseball? and the nats and padres still suck?” most of the copy in those rankings tends to be “X had a good week, driving in 9 runs and hitting 4 extra base hits.” the stories mainly chronicle the illusory trends of baseball; you probably couldn’t do meaningful “power rankings” more than once a month.

the truth can't hurt you, it's just like the dark/ it scares you witless, but in time you see things clear and stark -- macmanus

by tom s. on May 15, 2009 12:46 PM EDT up reply actions   0 recs

power rankings can still change with

injuries, performances against particular teams, player tendencies, etc. each week. I just think if a team that was winning every game for 5 weeks suddenly goes .500 for one week, they shouldn’t drop in a power ranking. They’re still the best team.

Now . . . if their star pitcher goes on the 60 day DL, then yes, they should drop.

On with the (good) youth movement!

by aet15 on May 16, 2009 5:42 AM EDT up reply actions   0 recs

For a ranking system that is all data based,

wouldn’t a good way to adjust the rankings for an injury to a key player be to count recent performance? For instance, the Dodgers lost 4 of 5 when they first lost Manny. The Cards lost 4 of 6 starting the game that Ankiel got hurt. Taking into account their last 10 games could help to account for the fact that they don’t have certain players anymore and their level of play will likely be affected.

The Godfather himself has decided to grace us with his presence. This is his damn house. He sleeps 20 feet away.

by thegodfather on May 16, 2009 10:52 AM EDT up reply actions   0 recs

I like this

because it makes us look more like underdogs, and we usually play better as underdogs

4B - beer baseball bands blog
"The ball sank the pirate ship that had been docked in the river."

by Cards Fan in Chitown on May 15, 2009 12:07 PM EDT reply actions   0 recs

well said

we were at #3 on CBS Sportsline. I blame that for our recent poor performances.

On with the (good) youth movement!

by aet15 on May 16, 2009 5:47 AM EDT up reply actions   0 recs

Reply All

First off, I made a typo in the chart. San Diego’s percentage should be .397, everything else is the same.

Washington is not listed as the worst team because they’d won 6 of 10 and they are underperforming their pythagorean record. Arizona and San Diego had each lost 8 of 10. Washington was trending up while those two were trending down, and that’s where the results come from.

At the time of the posting, the Cards were in a 3-way tie for first, so it’s not outrageous that they aren’t ranked higher. Is 87 wins too far off from what we have expected?

Recent performance is what may give some indication of what the team will do in the immediate future. Recent performance also may take into account recent injuries to key players. I used the teams’ records in their last 10 games so it’s not like teams will get bumped up or down considerably from a 3-4 game winning or losing streak when it’s weighted at 10%. However, teams that slump badly will fall down the rankings, as they probably should.

Strength of schedule is not that important. The reason I weight it relatively heavily is that SOS clusters around .500 for every team. This means that it will bring slumping teams’ overall ratings up and hot teams’ overall ratings down.

As for the games played not mattering in predicting future performance, I disagree. Obviously just because X team has won at Y percent so far doesn’t mean that they will continue at that pace, but it’s fairly safe to say that the proportion won’t be too far off in most cases this far into the season. The run differential and SOS are both there to help balance out the numbers for the outliers.

I think it might be a good idea to add something that takes into account batting luck to what I already have. Perhaps I could take the mean team BABIP and compare it to each individual team’s BABIP. Something like (Power now) + (.2)(Mean BABIP – Team BABIP). This would raise the score for unlucky teams and lower it for lucky teams. The only question is, what multiplier should I use? Looking at both ends of the spectrum, a .2 multiplier would lower the Dodgers win total from 98.4 to 97.4, and raise the Padres win total from 64.3 to 65.3. I like this idea, but what multiplier do you think I should use? And should the multiplier get smaller as the season goes on?

Honestly, I don’t know how to account for pitching or defense. Pitching BABIP won’t really work because that’s a product of defense. The pythagorean win expectancy is about as close as I can get without some help. I don’t necessarily think that anything needs to be adjusted for this, but if there is some relatively painless way to do so, I’m all ears.

The Godfather himself has decided to grace us with his presence. This is his damn house. He sleeps 20 feet away.

by thegodfather on May 15, 2009 2:39 PM EDT reply actions   0 recs

You're an idiot.

This makes no sense. What the hell are you even talking about?

The Godfather himself has decided to grace us with his presence. This is his damn house. He sleeps 20 feet away.

by thegodfather on May 18, 2009 2:51 PM EDT up reply actions   1 recs

flagged!!

the truth can't hurt you, it's just like the dark/ it scares you witless, but in time you see things clear and stark -- macmanus

by tom s. on May 18, 2009 3:24 PM EDT up reply actions   0 recs

Success!

I just needed some sort of response from that epic comment above./

/Sarcasm**

**Kind of

The Godfather himself has decided to grace us with his presence. This is his damn house. He sleeps 20 feet away.

by thegodfather on May 18, 2009 5:02 PM EDT up reply actions   0 recs

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