what's gotten into mitch boggs?

one of the few bright spots in a bullpen full of frustrating outcomes has been mitch boggs.

after a brief flirtation with life as a replacement-value starter in 2008 and 2009, he has since settled in as a decent, though unspectacular reliever.

most remarkably, for a reliever who throws at 95-96 mph routinely, mitch boggs does not get a lot of strikeouts, hovering around an 18% K rate as a reliever. he gets a merely okay rate of swinging strikes - about 8.4%, or close to league average during his time in the majors.

fairly subtle changes have made boggs into a much better reliever this year, however. maybe most remarkably, he has (so far) posted his first better than average walk rate (6.4%).

if mitch ever figures out how to make a 95 mph fastball get guys to swing and miss a lot, he'll be a great reliever.

but i think it's worth taking a look at some significant changes in pitch selection this season, which may be influencing his outcomes this year.

the most striking thing is that boggs is throwing his four-seam fastball infrequently; where he had previously thrown a four-seam fastball 23.5% and 28.3% of the time in 2010 and 2011, he now throws the four-seam fastball as little as 9% of the time.

his sinker (also classified as a two-seamer by pitch f/x) has seen a rise in use from about 49% over the past few seasons to 55% of the time. this has encouraged weaker contact, pushing his GB rate up to a career high 54%.

the other remarkable thing is that boggs has put his change-up back into his repertoire. while he had abandoned the changeup early-on (using it less than 2% of the time in the last two seasons), he reintroduced it in spring training. unlike a lot of pitches introduced in spring training, this one has stuck.

the change-up is something he uses exclusively against left-handed batters. boggs, for a long time, was among the worst pitchers in the cardinals bullpen in facing left-handers, in part because his sinker-slider pairing didn't give him much in the way of options against lefties.

his xFIP split last season was 4.48 against LHB, while it was 3.19 against RHB. in 2010, it was 5.80 against lefties and 3.23 against righties.

while it's still early in the season, this year, he actually has a (likely temporary) reverse split: 3.24 xFIP against lefties, and 3.64 against righties. i don't think that it's likely that the year ends with that kind of split, but it's certainly heartening to see some evidence of improvement against LHB following adoption of the changeup.

of note, his changeup still doesn't move a great deal horizontally (breaking away from left-handed batters about 2 inches more than his 4-seam, and about 2 inches less than his sinker). this hasn't changed much since erik took a look at boggs back in 2009 over at future redbirds.

the increasingly anachronistically titled pitchers hit eighth also did an interesting evaluation of his mechanics earlier this spring, finding that he had smoothed out an often-irregular delivery.

the broadest theme of boggs' 2012 so far may just be simple improved control. he's walking fewer people because he's throwing more strikes, especially first-pitch strikes (67% in 2012, compared to 57% for his career). combining that with the weak contact he induces, and he's a pretty decent pitcher.

still looking for the day when he starts striking out 20% of the guys he faces, though.