What Is Going On With Glen?

The latter statistic is a point of pride for the closer.

“I know that I want to avoid home runs, strike guys out and not walk guys,” Perkins told MLB.com’s Rhett Bollinger in August. “If I can do that, and maybe even get a groundball, and even that it's that important to me as not walking a guy and those things. As long as I don't walk guys and don't give up home runs, I know I'm doing the right thing.”

But while he has limited the walks, he has been hit hard as of late -- allowing a home run in each of his last three outings -- and even raising concerns that there may be an injury in play. He told reporters that he was unable to finish his slider which even prompted an MRI of his shoulder to see if there was any damage.

No damage was found but the location of his sliders since August -- which have led to three home runs -- shows that something is not right:

In addition to his slider, there is also concern for his fastball. According to the Pioneer Press, an unnamed scout had watched Perkins’ September 4th outing and said that his “velocity was down a tick”. While it is more noticeable as he has scuffled as of late, Perkins’ fastball has been “down a tick” almost all season.

When the left-hander was converted to a reliever, he saw his average fastball velocity increase considerably from his days as a starter with the Twins. In 2011, he was averaging 93.9 but touched 98 several times. In 2012 and 2013, he was averaging 94.9 and throwing his fastball above 96 on a semi-regular basis. This season however Perkins has not had that same gas on the pitch that he had in 2012 and 2013. Just four of the 604 fastballs he has thrown this season were measured at 96 miles per hour or above:

Despite the drop in velocity, Perkins’ fastball has not been a liability this season. Yes, it has been turned into hits more frequently partly due to a higher line drive rate than past years but according to ESPN/TruMedia’s Hard Hit Average, it has not been hit that hard. Beyond that, Perkins has shown a better ability to locate his fastball in the strike zone -- he has his career highest in-zone percentage (59.6%) and tied his highest strike rate (70%). So the higher batting average on his fastball could be a product of attacking the strike zone and avoiding walks.

Still, this precipitous dip in velocity could be of concern for the front office with $17.25 million remaining to be paid to the closer. At 31 years old, Perkins is near the age where relievers start to experience a decline in their velocity, which also correlates to fewer strikeouts:

While relievers don’t lose a mile per hour against their peak fastball velocity until their age-32 season, the fate of the strikeouts-per-nine-innings is more closely tied velocity. Starting pitchers don’t lose a strikeout-per-nine until their age-32 season. And relievers? The dip begins a year earlier, during their age-31 season. Losing velocity could indicate that a starter’s likely to see a decline in performance — but we see that the ability to be effective (particularly in terms of strikeouts) is less affected by velocity than compared to relievers.

The difference for relievers who throw 92-to-95 or 96-to-98 is significant. This year, hitters are batting .267/.347/.412 with a 9.1% swinging strike rate on fastballs that range from 92-to-95. From 96-to-98, hitters have been less successful posting a .230/.305/.326 line with a 11.4% swinging strike rate. Being able to throw 96-plus is a definite advantage.

If it is an injury that has been acting as a governor for Perkins’ fastball, the good news is the year is almost finished. If it is age that is inhibiting his velocity, that is a different story.