Larry Rothschild: Is he worth re-signing?

Larry Rothschild is about to agree to a new contract to continue his role as the New York Yankees pitching coach. He was first signed to a three-year deal before the 2011 season and had previously been the pitching coach for the Chicago Cubs from 2002 to 2010. He was also the first manager in Tampa Bay Rays history, compiling an abysmal 205-294 record over 3+ seasons and was a major league pitcher in 1981 and 1982, pitching 8.1 innings over seven games.

Personally, it has seemed to me that he has not been a good pitching coach. He has been at the watch while Phil Hughes and Joba Chamberlain failed to live up to their promise, and both of them actually became worse pitchers during his three years. A.J. Burnett was a big-time free agent signing before 2009, and he also struggled in New York, before being traded to the Pirates and reclaiming some of the success he showed with the Marlins and Blue Jays. Even CC Sabathia has begun to slide over the past two seasons, although that could have more to do with his health and the mileage on his arm.

So I set out to see if I could determine how good or bad Rothschild has been as the pitching coach. There really isn't a whole lot of ways to do this. I decided to look at how the Yankees pitching staff has performed compared to their FIP, xFIP, and SIERA. My assumption is that if the pitching staff under-performed these other three measures, it could partly be due to the job performance of Rothschild.

Before that a quick review:

• FIP, according to Fangraphs, "measures what a player's ERA should have looked like over a given time period, assuming that performance on balls in play and timing were league average" based on the "results a pitcher can control: strikeouts, walks, hit by pitches, and home runs."

• xFIP, according to Fangraphs, "replaces a pitcher's home run total with an estimate of how many home runs they should have allowed" given a league-average home run rate on the number of fly balls they allow, since "home run rates are generally unstable over time and fluctuate around league-average."

• SIERA, according to Fangraphs, "doesn't ignore balls in play, but attempts to explain why certain pitchers are more successful at limiting hits and preventing runs," but rather looks at the impact of ground ball and fly ball rates, which "tells us more about the how and why of pitching."

Now, what all three of these measures attempt to do on an individual level, is to remove the influence of luck and sequencing from the results of a pitcher. However, they are more valuable on a single-season level. It is less useful to use these with pitchers who look lucky over a large number of innings (larger sample size). A great example is Tom Glavine, who is under-valued by FIP, xFIP, and SIERA, which he outperformed by his ERA over his 4400+ career innings.

Using this logic, I looked at the past three years of Rothschild's staff's performance, which totaled 4351 innings. This should be enough innings to take out most random variance or luck. I then compared it to the performance of the 18 pitching staffs who have had the same pitching coach over the past three seasons. I compared how each staff performed (ERA) compared to their FIP, xFIP, and SIERA. I then ranked them on each of these measurements, and multiplied these ranks to come up with an overall ranking system. Here are the results:

As we can see, Rothschild ranks eleventh out of nineteen pitching coaches studied. Overall, his pitching staffs have slightly outperformed their FIP, xFIP, and SIERA. His pitching staffs over the past three years have been the 10th-best in their performance compared to their xFIP and SIERA, and 12th-best compared to their FIP. His pitching staffs have been below the median in ERA (3.81), FIP (3.88), xFIP (3.86), and SIERA (3.79). So Rothschild has basically been slightly worse than the average pitching coach over the past three years.

How much of an impact could he reasonably have on the team? If we take the difference between his ERA and FIP, and contribute it fully to his work as a coach, he would be worth almost 30 runs, or about one win per season over the past three years. If we look at xFIP, he would be worth just over two wins per season. On it's own, that is really good, but compared to other coaches, that would be just below the median. For instance, Curt Young has created about four wins per season in the difference between his pitching staff's ERA and FIP, and almost eight wins in the difference between their ERA and xFIP. If we compare Young's FIP to Rothschild's FIP, there is about a one win per season difference. If you compare him to Rick Anderson, there is almost an eight win difference.

Now, I am not arguing that this is a fullproof way to compare pitching coaches. However, it does give us a basic way to compare pitching coaches. Going into this, I expected Rothschild to be near the bottom, given how I have weighed some of the more notable pitcher's failure to develop under Rothschild. This shows he is more likely a fairly average pitching coach, who won't hurt the team when he is re-signed. However, if we could steal Curt Young, it probably would be worth it.

So, what do you think, is Larry Rothschild worth re-signing, or should the Yankees look elsewhere?

****UPDATE:

Poster ctoon brought up a good point about how park affects could impact these numbers. I put together a chart showing the same study, but replaced ERA, FIP, xFIP, and SIERA with ERA-, FIP-, xFIP-, and SIERA-. The results do change. Rothschild moves up to 9th and Curt Young stays in first. The biggest jump is 8 spots up by Mike Maddux of the Rangers, moving from 13th to 5th. The biggest drop is Dave Righetti, who dropped 8 spots, from 6th to 14th. This would make sense, given the hitters park in Arlington and the pitchers park out in San Francisco.

Here is the chart:

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