What to Watch in 2012: Perkins' Slider

As we count down the days until pitchers and catchers report to Ft. Myers, I'm going to run a series of columns this week detailing some of the less high-profile story lines worth following in the 2012 season. We've heard plenty about the redemption quests of Joe Mauer, Justin Morneau, Denard Span and Francisco Liriano; in the coming days I'll be examining some other factors that could significantly impact the 2012 season. Today, I look at the pitch that turned around an embattled southpaw's career and could continue to entrench him as one of the game's best relievers.

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After averaging just 4.7 strikeouts per nine innings over the first five seasons of his MLB career, Glen Perkins made the switch to full-time setup duties last year and the difference was night and day. In 61 2/3 innings at the back end of the Twins' bullpen, Perkins struck out 65 batters, good for a 9.5 K/9 rate that was superior to any seasonal mark he'd put up since splitting the 2006 campaign between Double-A and Triple-A as a 23-year-old.

Improved health and the freedom to let loose in shorter relief stints aided an increase in velocity across the board for Perkins, but while his fastball gained a few ticks, his most impressive pitch was a devastating slider, which showed remarkably more bite than we've ever seen from it in the past.

According to the PitchFX data available at Brooks Baseball, Perkins threw his slider a total of 440 times between 2008 and 2010, inducing only 47 swings-and-misses (10.7 percent). Last year, his much improved version garnered 60 whiffs on 276 deliveries, spiking his rate to 21.7 percent. That included a 27.6 percent swinging miss rate on two-strike counts, where the spinner was a dominant and very frequently used weapon.

Perkins' supremely effective slider enabled him to completely neutralize right-handed hitters, making him one of the few left-handed relievers in the league worthy of trust against batters from either side of the plate in late-inning situations. If his mastery with that offering continues, we could see him closing games before long.