The Boof Breakdown

 

	MPH	Usage	WHIFF	Zone %
2007 - Fastball	91.9	58.3%	.071	63.4%
2008 - Fastball	91.7	58.1%	.100	68.1%

What is apparent is that Bonser still has very good control and decent velocity on his fastball.  As a matter of location, Bonser's control of his fastball was above the MLB average (64% MLB zone avg).  In terms of velocity though, Bonser's average on this pitch has dropped minimally in three straight seasons even though he does throw harder than his MPH indicates, hitting 93-94 regularly.  If he does maintain a full-time conversion to the bullpen in 2009, I would expect that his average velocity increases because he will no longer have to reserve gas as he would have as a starting pitcher.  He favored throwing it to lefties versus the right-handed counterparts (63% vs 52%) which will incite some to use that as a possible explanation why his success against left-handed batters has waned. 

 

	MPH	Usage	WHIFF	Zone %
2007 - Curveball	79.5	19.4%	.247	63.8%
2008 - Curveball	79.7	17.0%	.359	66.6%

Bonser's curveball went from a passable pitch in 2007 to a good pitch in 2008.  Nearly 35% of all swing put on his curve -- one that has a good -10 mph difference along with a large break -- missed.  The change in WHIFF may be due to the fact that he reduced the usage against left-handed batters from 2007 to 2008, which might be his key to success against those hitters. In 2006, he used his curveball 14% against lefties and they slugged .451 off of him.  In 2007, Bonser used his curveball 24% (350) of the time against left-handed batters.  That year, lefties slugged .563 off of him.  In 2008, he threw it less frequently, nearly 19% (177) and witnessed his left-handed slugging percentage drop to .486 this past year.  Conversely, he's thrown that pitch more excessive each year to righties:  In 2006, it was 10% of his pitches to them.  In 2007, 14%.  In 2008 he was throwing it nearly 20% of the time.  In those three seasons, his right-handed opponents' slugging went from .469 to .360 to .405. 

 

	MPH	Usage	WHIFF	Zone %
2007 - Slider	85.6	16.5%	.204	63.4%
2008 - Slider	85.9	18.2%	.168	53.9%

In 2007, Bonser used his slider as his go-to pitch against righties, employing it 31% of the time.  This past year, it was thrown 24% to them instead mixing in more curveballs.  On occasion, he threw the slider to left-handed opponents but it was his main weapon-of-choice against the same-sided opponents (as should be the case since the pitch tends to break into the wheelhouse of left-handed batters).  As I had previously mentioned, the slider might be the main culprit for Bonser's inability to retire right-handed batters in the first-half of the season.  Bonser's slider, when effective, has a sharp downward motion.  The 2008 version of the pitch seemed to lack that bite.  Certainly it wasn't a pitch that the was hit hard -- he gave up just two home runs on this pitch -- but it wasn't fear either as his ability to throw it for a strike dropped.  I would wager that opponents' scouting reports reflected this zone degradation and subsequently batters chased it less which led to a lower WHIFF average. 

 

	MPH	Usage	WHIFF	Zone %
2007 - Changeup	82.2	6.1%	.068	61.5%
2008 - Changeup	82.9	6.6%	.206	58.7%

This was a pitch that Bonser wanted to mix in to his game more, he told the press this past spring.  It may have not inspired enough confidence or it could have been since his curveball actually provided a bigger discrepancy in velocity he used it as an offspeed pitch instead.  Regardless of why he did not follow his game plan, his changeup improved in 2008 as indicated by the handful more chases (.206 WHIFF) that in 2007.  Despite this improvement on the pitch, when Bonser enters the season in the bullpen, I anticipate that he will ditch the changeup in the 2009 season as relievers typically employ a three-pitch arsenal. 

 

As Bonser begins to accept his destiny as a relief pitcher in 2009, we will see a higher rate of fastballs thrown (~65%) at a higher average velocity (~93-94).  If used correctly, Bonser will face 70% right-handed batters and just 30% left-handed next season.  Right-handed opponents should see a nice split of 50% fastballs, 30% curveballs and 15% sliders with the rare changeup mixed in.  Lefties will see a higher percentage of fastballs (65%) and an even 15% each of the changeup/slider.