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.

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.