FanGraphs: 3 alarming spring performances

It has been a rough spring for a lot of pitchers, and while you can usually ignore spring training results, three guys in particular are pitching in a way that should worry you: Rich Harden (8 1/3 IP, 7 BB, 9 K, 2 HR), Madison Bumgarner (7 IP, 7 BB, 0 K, 1 HR) and Andrew Miller (7 2/3 IP, 8 BB, 2 K, 1 HR). But the most telling number can't even be found in their stat lines.

Harden is coming off another injury-riddled season, so spring training represents an especially important tune-up, while Bumgarner and Miller are young guys looking to get spots in the big league rotation. Each of these guys have some real incentives to bring their best stuff even in games that don't count. Walking seven guys while striking out none in seven innings as Bumganer has is very troubling, even if it is just seven innings. But even more telling is fastball velocity.

Over seven innings a pitcher throws about 60 fastballs, and a given pitcher's fastball speed does not vary by much, so 60 fastballs gives a pretty good picture of a pitcher's true talent. And fastball speed is tremendously important. The average fastball that is swung at is missed 14 percent of the time, and on average each additional 1.25 mph increases this rate by 1 percent. More swinging strikes mean less contact and more strikeouts. Not surprisingly, there is a clear trend showing that pitchers who throw faster perform better.

This is especially troubling for Harden and Bumgarner, whose fastballs have been noticeably slower during spring training. Last Monday the two pitchers actually faced off in the Ranger's spring training park in Surprise, AZ, one of the few springing training parks with the Pitchf/x system.

Harden's fastball was sitting in the 88 to 91 mph range topping out at 92.1 mph. His average speed last year was over 92 mph. Bumgarner worked in the 88 to 90 mph range, topping out at just 91 mph. He was regularity above 90 mph last year in the minors, and his fastball is his best pitch. However, his velocity did start to fade towards the end of last season, which makes his lack of velo this spring even more concerning. Some pitchers can succeed with a slower fastball, but the reduced speed coupled with the very poor performance is not encouraging.

Miller is a cautionary tale for Bumgarner about what can happen when a pitcher's velocity goes away. Once an elite prospect who could regularly throw 95, his average fastball just 90.9 MPH a year ago, and his stock has tumbled significantly. A disastrous spring certainly won't help get him back in the Marlins plans.

It's always possible these guys are still a step behind after a long winter, and that their velocity will return. But when trying to figure out which spring training stat is most telling for pitchers, start with fastball velocity.

Dave Allen is an author of FanGraphs.