2019 report cards for starting pitcher hooks

A couple years ago, I brought out VEB’s good ole Mathenaging story tag and wrote about Matheny’s proclivity to allow his starting pitcher to remain in the game more so than his managerial peers. I found that his starting pitch hook in particular actually cost the Cardinals over a win’s worth of runs that season. Indeed: it was the best worst of times, it was the worst of times.

Having now completed the first full season of the Mike Shildt era, I decided to repeat my earlier exercise to see if the Cardinals were faring any differently under the latter. I’d recommend you read the original piece if you’re curious as to the methodology, but the long and the short of it is that I looked at how a team’s starting pitchers performed when being left in the game during a high leverage plate appearance the third time through the order versus how well that same team’s bullpen performed in 2019.

If that seems like a hyperspecific filter, just keep in mind that there were numerous variables I needed to account for.

In many instances, the second time through the order is simply too early for a manager to go to his bullpen without expanded rosters.

Stats from the fourth time through the order become too unstable to use for two reasons: 1) The sample size drastically shrinks; 2) Starters lasting that deep into a game are likely the beneficiary of “survivor’s bias”. (Not only is this a more talented group to begin with–how often do you see a terrible pitcher toss a complete game?–, but they have also been pitching exceptionally well on that particular day.)

Managers are more willing to push the envelope with their starters in low leverage, blowout games. Is it worth burning a reliever for tomorrow to keep one or two runs off the scoreboard in the seventh inning of a 9-0 landslide?

First, I compared the starting pitcher weighted-on base average (wOBA) allowed in such situations versus the wOBA each club’s bullpen yielded. A negative value indicates that a team’s proverbial hook resulted in them leaving in a starter when their bullpen likely would have performed better.

Recall that in 2017, St. Louis ranked dead least in terms of net wOBA. While the Cardinals’ bullpen was slightly above average that year, it certainly was not the second best in baseball like it was this season. The Cardinals’ rotation also performed better, supporting the groundbreaking hypothesis that have good pitchers makes managing easier.

Let’s also take a look at how many runs–and wins–the above values actually translated into.

To compute raw run values I turned to wRAA, which measures total offensive value. (wOBA works on a per-plate-appearance basis, not crediting managers who make fewer mistakes to begin with.) From there I could find the win value of a manager’s starting pitcher hook by using the 2017 cost of a win: 10.057 runs.*

*In 2019, this figure was 10.296 runs-per-win

Some takeaways from this table:

• Keep in mind that the wins “added” column is a very rough estimate, since it doesn’t take into account that these are high leverage plate appearences.
• The Cardinals allowed their starting pitchers to remain on the mound the 11th most frequently, still a significant step up from ranking second highest over the course of Matheny’s tenure.
• On the aggregate, managers are getting better! While still at an average negative value, they cost their teams about a run less than two seasons ago.
• As the astute reader will notice, Kansas City finished last on both lists, even without–well, you know. On the bright side, Royals fans: it can’t get any worse than it already is.