Through 21 games, the bullpen of the St. Louis Cardinals ranks 13th, 10th, and 5th in ERA (3.25), FIP (3.42), and xFIP 3.35), respectively. The bullpen contains four relievers with an ERA better than the team average and three with an ERA worse than the team average. One of the relievers with an ERA worse than the team average is the 27-year-old Seth Maness, who, in eight innings pitched, has posted a 6.75 ERA, 3.86 FIP, and 4.82 xFIP. Considering a sample of eight innings is essentially one good start for a starting pitcher (and even less meaningful for a relief pitcher), I will no longer discuss Maness' 2016 statistics. However, when you look at Maness' PitchF/x data thus far in 2016, it is impossible to ignore the warning signs.
Pitch Velocity, 2013 through 2016 (Data via BrooksBaseball.net)
It is completely natural to see a decline in velocity as a pitcher ages. That being said, Maness is still only 27 years old (and entering an age range where All-Star starting pitchers, oftentimes with over a thousand innings already logged, sign $180+ million free agent contracts), so I would not necessarily consider him a true candidate for a substantial dip in velocity across the board.
Yet, this is exactly what we have seen thus far in 2016. Now, I understand that sometimes it takes a few months for some pitchers to get their velocity up to where they want it to be (we saw this with Rosenthal last season), but this has not been an issue for Maness who had started each of his first three MLB seasons with an average fastball velocity north of 90 MPH. He then saw an uptick to ~91 MPH during the hot summer months, but regardless, he never started below 90 MPH, something he has done as the first month of the 2016 season comes to a close.
In a vacuum, a decline in fastball velocity is already a problem, especially for a pitcher with fringy, at best, velocity in the first place. Now, I am well aware of the commonly-cited anecdote that "tired sinkerballers can be more effective" because they experience more drop on their sinkers, but even with Maness' decline in velocity (can be correlated with the "tired sinkerballer" narrative), he has not subsequently experienced a noticeable increase in drop on his sinker, or any of his pitches for that matter.
Outside of the aforementioned vacuum, a decline in fastball velocity can also be detrimental to the other pitches in a given repertoire, particularly the changeup. The desired velocity difference between a fastball and changeup is eight to 10 MPH. As I have discussed in the past, many people use eight to 10 percent (instead of MPH), but with pitchers throwing in the 90 to 95 MPH range, it really does not matter all that much. Either way, the difference between Maness' average fastball and changeup velocity thus far in 2016 is 4.78 MPH. A hitter could be completely fooled and still make solid contact given such a small magnitude of difference between the two pitches. If Maness' decline in fastball velocity is here to stay (let's hope it isn't), he may have to modify his changeup grip in order to take off a few MPH to get closer to the desired velocity difference.
Lastly, while Maness technically throws four different pitches, from purely a velocity standpoint, his four pitches essentially fall into two groups. His fastballs are very similar in velocity, and his changeup and slider are very similar in velocity. Ideally, a pitcher, especially one that cannot blow a hitter away, has a third velocity he can dial into when necessary. Maness, with his current repertoire, does not have that third velocity he can utilize to keep hitters off balance.
Pitch Location, 2016 (Via BrooksBaseball.net)
From a location standpoint, Maness has actually been pretty good as the overwhelming majority (66.67%) of his pitches have landed in the bottom two rows of the zone. However, pitches missed up in the zone have resulted in solid contact by opposing hitters (insert sample size disclaimer here). When I look at the heatmap side-by-side with Maness' current statistics, I am even more worried than before because as you can clearly see, Maness is not having much trouble with pitch location, yet hitters are still enjoying success against the sinkerballer. On the flip side, given the extremely small sample, this heatmap could also be seen as a good sign, with much of Maness' poor performance being attributed to bad luck (.412 BABIP thus far).
Double by Eugenio Suarez on April 16, 2016
After being gifted an inside strike call on an 88.2 MPH sinker, Maness followed with a center-cut 83.3 MPH changeup. Relatively speaking, it may have been down in the zone, but from a horizontal location standpoint, it really could not have been any meatier of a pitch for Suarez, as he promptly deposited the changeup into the left-field corner for an RBI double.
In fairness to Maness, it is not necessarily easy for a right-handed pitcher to be consistently successful with his changeup against right-handed hitters, unless, of course, you possess a changeup of similar quality to Carlos Martinez's or Trevor Rosenthal's. One of the pitch's primary purposes for righties is to induce swings and misses by left-handed hitters on pitches down and out of the zone.
Thus, in order for a right-handed changeup to be successful against a right-handed hitter, it must be sequenced and located well. While Maness sequenced the pitch well by throwing his sinker on the pitch prior, the velocity difference (as discussed above) just isn't where you want it to be at this point and as discussed in the paragraph immediately prior, the location was poor, at best.
Things are not good for Seth Maness right now. While he may be locating his pitches well, the makings (velocity, movement) of these pitches are simply not desirable at this point. I hope Maness is able to figure it out soon because I have a strong feeling his manager will continue to run him out there for important situations going forward, regardless of past and current performance.