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Luke Weaver should be in the St. Louis bullpen

If the Cardinals are going to stay in this thing, they need to take every advantage they can get.

St Louis Cardinals v Pittsburgh Pirates Photo by Justin K. Aller/Getty Images

The Cardinals continue to have a streaky season. After a seven game losing streak prompted me to look at the prospect of selling at the deadline, the Cardinals have won three straight. John Mozeliak said that they will take the next 4-6 weeks to evaluate things, and noted that selling has to be an option. The Cardinals have a bit of a mountain to climb in the Wild Card race, sitting 8 games out. The division race is closer, with them being just 2 1/2 games out. Catching up to the Brewers may not be tough, but the Cubs sit 1 12 in front of the Cardinals as well.

If the Cardinals climb back into things, they’ll likely be looking for bullpen help. The bullpen has been lacking, costing the team several leads as well as putting pressure on manager Mike Matheny to sometimes leave his starters in longer, which can also backfire. Using some park and league adjusted stats, lets look at the how the Cardinals’ pen has performed on the year:

Cardinals 2017 bullpen ranks.txt

Team stat score rank
Team stat score rank
ERA- 113 24th
FIP- 102 20th
xFIP- 106 24th

These stats are park and league adjusted versions of ERA, FIP, and xFIP, and give a score in terms of percentage above or below average. For instance, the Cardinals 113 ERA- means the bullpen has given up 13% more runs than average, given the parks they’ve played it.

They’ve surrendered more runs then expected, given the fielding-independent stats. They still rank solidly near the bottom in terms of xFIP- though, with some homer-suppression making things look better in terms of FIP. The Cards’ relievers have some disappointing results, and the strikeout, walk, and fly ball numbers back that up.

The good news is that the projections expect better performance going forward. Fangraphs’ depth charts don’t show projected FIP-, and just using FIP would ignore differences in run environments across the league. They do however, project innings pitched as well as WAR. Using WAR alone would reward bullpens that need to throw more innings, either because they have more games remaining or their starters don’t go as long. Using WAR with innings pitched, here’s each team’s bullpen’s WAR per 65 innings pitched (a typical shorthand for a full-season from a reliever):

The Cards rank 8th by this measure, inside the top third. That’s quite a swing from the results, and reminds us that even a couple of months of under-performance from the bullpen still makes for a small sample when projecting future performance. To get to the bottom of this, let’s break things down by reliever. We’ll look at the current bullpen, plus the recently demoted Miguel Socolovich, who had been with the team the whole year. Here’s their projections at the start of the year as well as now, along with their performance in 2017:

Cardinals 2017 Bullpen makeup.txt

Player Preseason projected FIP 2017 FIP 2017 xFIP ROS projected FIP
Player Preseason projected FIP 2017 FIP 2017 xFIP ROS projected FIP
Trevor Rosenthal 3.39 1.94 1.87 2.99
Seung Hwan Oh 2.89 3.84 4.94 3.22
Brett Cecil 2.90 4.93 4.52 3.36
Matthew Bowman 3.73 3.16 3.67 3.65
Miguel Socolovich 3.51 5.34 5.36 3.83
Tyler Lyons 3.65 5.31 6.19 3.95
John Brebbia 4.11 6.09 7.33 4.07
Kevin Siegrist 3.95 4.89 4.94 4.22

Since beginning the season, Trevor Rosenthal has essentially leapfrogged Seung Hwan Oh and Brett Cecil in terms of expectations going forward, but those continue to be the best three, despite Cecil’s woeful start. Perhaps either Oh or Cecil can get things straight again, and form an effective late-inning duo with Trevor going forward.

Even if that happens though, it would be nice to add a third strong reliever. Having capable relievers handle the last three innings would be nice for maximizing the chances of winning close games, something they’ll need to do if they’re going to contend down the stretch.

If the Cardinals are buyers at the deadline, expect them to be in the market for relievers. They’ve commonly dealt for relievers in the past. Those they’ve acquired have often been underwhelming. That’s because they generally only are willing to part with fringe talent for those relievers.

Production from relievers, on a per WAR basis, is generally much more expensive than other players. While I found the average price of a win in the last off-season to be $9M, for relievers it was $20M. Add-on that the cost of in-season wins are about double the cost they were in the most recent offseason, and you can see why acquiring wins in the form of relievers can be very costly at the deadline. Take David Robertson’s trade value, a strong reliever who is likely to be moved at this year’s deadline:

David Roberson Trade Value Calculation.txt

David Robertson 2017 2018 Total
David Robertson 2017 2018 Total
Price of WAR $40.00 $21.00 $26.00
Projected WAR 0.5 1.3 1.8
Projected Value $18.40 $27.30 $45.70
Salary $4.00 $13.00 $17.00
Projected Surpus $14.40 $14.30 $28.70
Projected NP Surplus $14.40 $13.20 $27.70

Combined with my aggregate top MLB prospect list, which aggregates the implied value that six public top prospects lists attributed to the game’s best prospects, and you see that Robertson’s value should bring back a decent haul. His value is closest to the 49th ranked prospect according to my list, Jake Bauer of the Rays. Most deals involve multiple prospects though, so the main piece going back probably won’t be ranked quite that high. Luke Weaver is the 67th ranked top prospect, with a estimated value of $22M. He could make a swell main piece going back.

However, rather than part with an MLB-ready pitcher that has six years of cheap control remaining, why not just use Weaver himself? After all, Weaver struck out more than 11 MLB hitters per nine last year, while walking less than three per nine, leading to a well-above average starter xFIP of 3.34. He did experience some homer issues, but over 36 innings, home runs numbers can be pretty noisy. That’s why over a small sample it’s best to use xFIP instead of ERA or FIP.

Weaver isn’t the only prospect that could improve the Cardinals’ bullpen right away. There’s also Jack Flaherty, who did great in his first taste of the upper minors in Double-A, before recently being promoted to Triple-A. Let’s look at their stats in 2017, as well as how they project to pitch in a major league bullpen.

Weaver and Flaherty 2017 stats.txt

Prospect level FIP xFIP projected MLB bullpen FIP
Prospect level FIP xFIP projected MLB bullpen FIP
Luke Weaver AAA 2.81 3.18 3.12
Jack Flaherty AA 2.34 3.02 3.79

If you go to Luke Weaver’s Fangraphs page, his projected FIP is higher than shown here. However, that’s because he’s projected as a starter. Last year, I found that pitchers on average lose 0.65 points of FIP when moving from starting to relieving. I don’t know how the projections themselves would adjust to the change, but I bet taking 0.65 points off his projection gets us much closer. Flaherty’s projection is not adjusted, because his projection is already for pitching out of the bullpen.

Looking back at the Cardinals’ current bullpen make-up, this projection would rate Weaver as the second-best option out of the pen. Flaherty would rank as the fourth best option, fifth-best if Weaver is in the picture. Both options have already shown that they can be very effective against upper minors hitters. Perhaps now is the time to see how they do against major league ones.

The Cards also have the flexibility to promote both. The team’s worst projected relievers going forward - John Brebbia and Kevin Siegrist - both have options remaining, so they can be sent to the minors without risking any loss.

The biggest flaw to this plan would be the fact that Weaver is the team’s presumed sixth starter should the rotation incur a long-term injury. He’s already stretched out as a starter though, and I don’t think a few weeks as a reliever will make a big impact on his ability to change back to starting again if needed.

There’s also the fact that Jack Flaherty is only 21, and long-term, it’s probably best to focus on his development. This is his first season facing the advanced competition of the upper-minors, so there’s no rush. Still, he’s performed extremely well and perhaps a cup of coffee in the major league bullpen would help highlight the things he should be working on in the minors. If inning totals became an issue, he could always head to the Arizona Fall League or a winter league if necessary.

What can the two’s performance this year say about their prospective numbers in the minors? That’s something I wanted to find out. So I grabbed every pitching season in Triple-A over 20 innings, and selected for those who had at least 70% of a pitcher’s appearances coming as a starter. I also found each case of a major leaguer pitching 20 or more innings out of relief, at matched up each case of a pitcher doing both in the same season. I then found the average difference between the stats at both levels:

Triple-A starters to MLB relievers.txt

Cases 128
Cases 128
K/9 difference -0.20
BB/9 difference 0.60
FIP difference 0.16
xFIP difference 0.14
AAA xFIP to MLB FIP 0.10

Triple-A pitchers as a whole only add 16 points of FIP on average when moving to an MLB bullpen. Even closer, a Triple-A starter’s xFIP is only 10 points lower than his Major League bullpen FIP. For specific players, the relationship isn’t great. You wouldn’t really expect it to be, when using 20 innings pitched as the threshold. The important part is that the difficulty of getting hitters out as a starter in Triple-A is fairly similar to getting MLB ones out as a reliever. The advantages of being a reliever almost make up for the higher quality of competition.

The same is true at the Double-A level:

AA starters to MLB relievers.txt

Cases 44
Cases 44
K/9 diff -0.17
BB/9 diff 0.51
FIP diff 0.32
xFIP diff 0.34
AA xFIP to MLB FIP 0.17

I don’t want the Cardinals to keep Weaver and Flaherty in the pen for good. Both have a chance to be future rotation stalwarts. For one, I think Weaver should be next in line for a permanent spot in the rotation, possibly as soon as someone gets injured. And for Flaherty, more innings means more development, and at 21 that should be the focus.

However, if the Cardinals want to compete this year, they’re going to have to push every advantage they have. Weaver has shown to be superior to upper-minors competition. Right now, he projects as one of the team’s best options in the bullpen, an area that has been holding the team down. In terms of development, Weaver should probably be facing MLB hitters anyway, and learning how to get them out.

Flaherty isn’t quite at that point, but right now present wins top the developmental concerns, and he could be an upgrade over the current options. The Cards have a month and half before the deadline, and they should be trying to put themselves in a position to win as much as possible. If it doesn’t work, Flaherty goes right back to the minors to continue development. If it does work, the bullpen could end up being a strength down the stretch, rather than a weakness.