January 20, 2012

Fantasy Beat

David Ortiz's Strikeout Improvement

by Jason Collette

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In 2011, David Ortiz did David Ortiz things as he challenged 30 home runs, nearly drove in 100 runs, and surprised fantasy leaguers by hitting .309 last season. This came off a 2009 season in which he hit just .238 and a 2010 season in which he hit .270, so a 39 point spike in his batting average was rather surprising. One of the reasons why Ortiz was able to hit over .300 for the first time in four seasons was his dramatic reduction in strikeouts. That was certainly the easier way to do it because hitting over .300 while striking out 120 or more times is a tough feat to accomplish. Matt Kemp, Alex Gordon, and Mike Morse all did it this past season, but they are just three of 37 players to do so out of the 934 players who have struck out at least 120 times in a single season.

In 2008, Ortiz struck out in 15 percent of his plate appearances and hit .264, then saw that strikeout rate climb to 21 and 24 percent over the next two seasons. When his batting average on balls in play fell to .262 in 2009, his average fell to .238. In 2010, the strikeout rate was 24 percent, but he hit .313 on balls in play and was able to hit .270 on the season. Last season, his BABIP went up another eight points and he reduced his strikeout rate more than any other everyday player over the past five seasons, allowing him to hit over .300 for the fourth time in eight seasons. When people were drafting Ortiz last season, it was mainly as a two-category player because his days as a strong average hitter appeared to be over. Oops.

We know from Russell Carleton's work that strikeout rates need at least 150 plate appearances for stability. We also know that last season, Ortiz's strikeout rates per month were 33, 26, 21, 29, 22, and 17 percent. Had we been looking at that second-half trend in 2010 while the Red Sox batters were dropping like flies, we may have had a heads up on what was to come in 2011. We know that over the first 456 plate appearances in 2010, Ortiz struck out 25 percent of the time but dramatically cut into that over his final 150 plate appearances in 2010, striking out exactly 20 percent of the time.

His 2011 monthly splits were even more encouraging, as his strikeout rates by month were 11, 10, 13, 18, 17, and 15 percent. Whatever adjustments Ortiz made during the latter half of 2010 to how pitchers were throwing to him in 2009 and the first half of 2010 carried into 2011.

Our stats group went back over the past five seasons and pulled a report showing instances of hitters with at least 400 plate appearances in a single season and how their strikeout rates changed for the better the following season. Maybe diehard Red Sox fans noticed what Ortiz did in the second half of 2010 and were hopeful that he would reduce his strikeouts somewhat in 2011, but to improve it 43 percent in one season exceeded even the biggest homah's expectations.

If we were to consider a 25 percent improvement in strikeout rate from one season to the next a significant amount, we see just how tough it is to do. Of the 500 instances in the sample pool, just 37 hitters improved that much from one season to next; that represents just seven percent of the sample size. The hitters that make up the player pool read off like an Ellis Island manifest as it has the young, the old, the tired, the big, and the small.

Several players, such as Delmon Young, Mike Napoli, Dioner Navarro, and Justin Upton, enjoyed career-best seasons at the plate in the season in which they made a significant reduction in their strikeout rate. That list is also contains a healthy dose of light-hitting middle infielders as well as some notorious free swingers. The list is fairly representative of all player types in baseball: the fast (Reyes), the slow (Butler), the small (Eckstein), and the large (Napoli). Strikeout rate improvement can happen for any player, but how much a player can improve in one season varies greatly.

The average rate of improvement for the hitters that showed a reduction from season A to season B was just 13 percent. If we reduce our player pool to only those players that struck out at least 20 percent of the time in season A, we are left with just 134 of the original 500 players, but that did not change the average level of improvement.

This past season, Evan Longoria had a 15 percent strikeout rate over his final 155 plate appearances while striking out in 17 percent of his plate appearances leading up to that point. Longoria's strikeout rate by season: 24, 21, 19, and now 16 percent. Jon Jay had a 13 percent strikeout rate over final 150 plate appearances and was also striking out at a 17 percent clip up until those final 150 plate appearances.

When drafting players and worrying about average, we do not have too much to look at outside of second half trends and hoping those developments did not get lost in the down time of the off-season. Do watch those first 150 plate appearances in 2012 with certain players because if they are demonstrating a significant change in contact, there is an excellent chance those improvements are for real and you could be in store for a pleasant batting average surprise, as many Ortiz owners were this past season. Don't ignore a player's track record, but a quick change in strikeout rate is more likely to be legitimate than a quick change in most other stats.

Jason Collette is an author of Baseball Prospectus. 
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