It’s no secret that Barry Zito has undergone a mini career renaissance this year, clawing his way back from two sub-par seasons that had many calling his contract the worst free-agent contract ever to post some surprisingly solid numbers this year. His FIP is the best in four seasons, and his K/9 is the best he’s posted since way back in his 2002 banner season.

As has often been noticed, Zito’s decline has been a product of two things – a loss of velocity on a fastball that was already marginal at best, and a loss of command over his big looping curveball.

While Zito’s fastball velocity has inched up a bit this year, and his command is slightly better this season, neither has improved very significantly, and pretty much all other peripheral numbers are right at career norms.

No, the one big difference between 2009 Barry Zito and all other Barry Zito’s is that he is suddenly throwing a new pitch a lot more often – an 80 mph slider with good command.  This slider has allowed Zito to get more K’s and have another option to get a strike over without having to always grove his 86 mph fastball right down the pipe.

When Zito first came up and dominated in the early years of this decade, he was basically a strictly fastball-curveball guy, mixing in an occasional changeup only about 15% of the time.

10 seasons later, he is still throwing his changeup about 15% of the time, but instead of throwing his fastball 60% of the time and his curveball 25%, he is now mixing in a slider.

Zito began experimenting with the slider as early as 2005, but until this year it was still an experimental pitch which he only threw on rare occasions (only about 7% of his pitches).  But this season he is throwing the slider almost 18% of his pitches, and it’s been the main secret to his increased effectiveness.

Jamie Moyer is getting hammered this year.  His ERA is an unsightly 8.10, his WHIP is a bloated 1.84, and he has allowed at least 4 runs or more in 6 out of 7 starts so far.

What’s odd about this is that for decades now, Moyer has been an almost machine like model of consistency.  Year after year he kept going out there, slinging 82 mph fastballs with pinpoint control.

Moyer’s velocity has been in very very gradual decline, on average losing about 2/10 of an mph per year over the last decade, but the year-on-year decline is almost infinitesimal.  Moyer’s K/9 rate certainly hasn’t declined, and he hasn’t been a victim of bad luck with BABIP.

What really stands out as different this year is Moyer’s pitch selection.  After years of consistently throwing about 40% fastballs, Moyer is mysteriously throwing 61% fastballs in 2009. Not a very good idea when your fastball is sitting at 81 mph.

Moyer used to be famous for his devastating changeup, but for reasons which are not entirely known, his changeup use has declined every year over the past 8 years, from 35% in 2002 to 20% this year. He also almost entirely stopped throwing the big knuckle curve he used to feature in his glory days, which is down from 20% to a mere 4% of pitches.

In recent years Moyer had made up for the decline of these two pitches by adding a cutter, which he first featured on occasion in 2004, and gradually ramped up to his main secondary pitch, at 30% last season.

But this season, his cutter too, has fallen off a cliff, and is dramatically down to only 14% of pitches.  Meanwhile, the percentage of Moyer’s pitches which cannot be identified by the Pitch F/X people, usually in the low single digits, is up to 16%.  These pitches tend to be junk balls – not slow enough to be changeups, not fast enough to be fastballs, and not moving enough to be breaking balls.

The result is a pitcher whose pitch selection profile is drastically different from his career norms.  To my knowledge Moyer has never thrown such a high percentage of fastballs and fastball-like pitches, and with his velocity, there’s no good reason he should be.

My best guess is that Moyer has started losing the ability to control his pitches, forcing him to throw more fastballs in the zone. This would also help explain his elevated walk rate, his highest since 1991, which was eons ago in baseball time. He seems to have lost his feel for the cutter, his faith in his changeup is lessened, and his curveball is all but disappeared.

We are still in the region of small sample size, but we are quickly reaching its frontier, and Moyer’s ungodly consistency all these years makes such big fluctuations all the more odd.  Moyer’s ERA has bounced around from year to year, but his underlying numbers have been almost like unto clockwork.  But Jamie Moyer is 46 already, and his long and storied career may finally be coming to an end.