Did Yu Find the Strike Zone?

Yu Darvish‘s successful first year in the U.S. was full of some ups and downs. His fantasy owners should have been happy with his final results of 16 Wins, a sub-4 ERA, especially in Texas, and 221 strikeouts. Some signs point to Davish improving during the 2012 season and those changes may follow him into the 2013 season.

With any player’s first season in the majors, it is tough to evaluate their production going forward with so few of stats. The key, IMO, is to look where the player is making improvements or degrading over the course of the season.

The first positive sign was his ability to maintain constant fastball speed over the course of the season.

Another factor bringing down Darvish’s value is the number of walks he gave up (4.2 BB/9, 11.9 BB%). The 26-year-old right-hander’s walks inflated his WHIP (1.28) quite a bit. Over the course of the season, he lowered his walk rate which at times was over 6 BB/9. Most of the gains were towards the end of the season.

The key to lowering the walk rate was throwing more pitches into the strike zone. During the last month of the season was the only time his Zone % was over 50%

Month: Zone %
Apr: 47%
May: 47%
Jun: 49%
Jul: 45%
Aug: 46%
Sep: 52%

With the increase number of pitches in the strike zone, his strikeout rate also improved over the course of the season.

Month: K%
Apr: 23%
May: 26%
Jun: 27%
Jul: 27%
Aug: 31%
Sep: 29%

A couple of the previous stats are a bit of concern though. Pitchers who have problems throwing the ball over the plate historically have been more prone to injuries than other pitchers. Pitchers with a BB% greater than 10%, Darvish was at 11%, have an almost 50% of ending up on the disabled list the next season. Also, those pitchers with a Zone% of 47% or less go ~50% of the time to the DL. Darvish barely missed this mark at 47.7%.

Going into the season 2013, the key factor to look with Darvish is his ability to throw strikes. See if his Zone% is near 50% and buy, if not, stay away. Over the last month of the season, once he got the walks down, he ERA was at 2.21 (1.89 FIP). Darvish may be a pitcher to take chance on having an improved 2013 season.

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Jeff writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won three FSWA Awards including on for his MASH series. In his first season in Tout Wars, he won the H2H league. Follow him on Twitter @jeffwzimmerman.

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Interesting read, thanks.

I’m under the assumption that the typical pitcher with high BB issues has poor mechanics or is over-throwing to compensate for being a poor pitcher which both can (will) lead to injuries.

I don’t think either of those are an issue for Yu, from what I understand (perhaps incorrectly) the Japanese leagues had larger (more for-giveable) strikezones, with perhaps less patient hitters. Nibbling was a weapon for a pitcher.

I think Yu had to adjust to the MLB strikezone/hitters and he’ll continue to do so.

Travis L
Travis L

Where did you hear that information about poor mechanics / over-throwing causing high BB issues?


I didn’t really, I said “assumption” and was based on personal observations and guess-timates.

And admittedly, I overlooked the link in the above article to Jeff’s article doing the math.