Is the MLB strikeout rate continuing to rise?

You probably know that strikeouts have been on the rise since 2008. There was a pretty steady climb between 2008-2012, when the major league strikeout rate was just a shade under 20 percent. The league rate was essentially the same in 2013, giving an appearance that strikeout rates would stabilize or perhaps decrease. However, the first two weeks of the 2014 season indicate otherwise.

Here's a look at the average strikeout rates for starting pitchers in the first month of the season.

Strikeout rates for relievers have been rising as well, and there's a big boost at this point in 2014.

What's behind the increased strikeouts? As it turns out, it's the usual culprits, fastball velocity. In April/March, the average fastball velocity for starting pitchers has ranged from a low of 89.8 in 2008 to 90.8 in 2012. Right now, the average fastball for a starting pitcher is 91.4 miles per hour. Pitchers, as a whole, tend to throw slower in March/April than at any other time of the year. Either everybody is maxing out right now, or there has been a significant bump in average fastball velocity.

Relief pitchers also have a higher strikeout rate, though their fastballs aren't outpacing those of relievers in 2012 or 2013. Similarly, relief pitchers aren't throwing more off speed pitches and thus far, things appear comparable to the last two seasons.

There are a lot more starting pitchers throwing serious heat now than ever before. Last year there were 12 pitchers who made at least one start in March/April and averaged at least 94 miles per hour with their fastball. This year there are 25 such hurlers, and they have a combined strikeout rate of 23.8 percent. Fastball velocity correlates with strikeout rate at 0.46, and increases or decreases in an individual pitcher's fastball velocity have a greater correlation with strikeout rate (anyone who says velocity doesn't matter is either lying or Mark Buehrle).

A good chunk of these pitchers are new arrivals. Yordano Ventura, Garrett Richards, Nathan Eovaldi, Gerrit Cole, Jarred Cosart, Zack Wheeler, and James Paxton, just to name a few, weren't in the big leagues last spring. Others are guys who seem to have found some extra velocity. Wily Peralta, Brandon Morrow and Johnny Cueto are all showing more velocity than they have previously. Even Brandon McCarthy is clocking in at 93 miles per hour (color me skeptical on that one, he's previously averaged between 89-91).

Furthermore, it appears that teams are placing more emphasis on catcher framing, and called strikeouts are also up from last year. Not-overly-deft glovemen such as Carlos Santana and Ryan Doumit are spending less time behind the dish, and the likes of Mike Zunino, Travis d'Arnaud and Ryan Hanigan are seeing more time. Better baseball minds than my own have predicted a growing emphasis on framing and a corresponding rise in strikeouts last year.

All this doesn't necessarily mean that strikeouts will stay above 20-21 percent the whole season. As those first tables showed, strikeout rates were higher in April 2013 than in April 2012 for both starters and relievers. But, by season's end major league strikeout rates for 2013 were essentially the same as those for 2012. It does appear that fastball velocity is on the rise though, and hitters can't be too happy about that.

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Stats courtesy of Fangraphs and Baseball Savant

Chris Moran is a former college baseball player and current law student at Washington University in St. Louis. He's also an assistant baseball coach at Wash U. In addition to Beyond The Box Score, he contributes at Prospect Insider and Gammons Daily. He went to his first baseball game at age two. Follow him on Twitter @hangingslurves