Lance Lynn's declining peripherals are concerning

Over the last few years, Lance Lynn has been perhaps one of the most underrated pitchers in baseball. He has been a constant in the Cardinals rotation since the start of 2012, making 122 starts and posting a solid 3.39 FIP over that time period. His 12.7 fWAR since the start of 2012 is 20th among all major league pitchers.

For much of this season, it appeared as though Lynn was pitching even better than he had in the past. At the end of July, Lynn had a 25.5 percent strikeout rate, a 7.6 percent walk rate, and a sterling 2.82 FIP in 19 starts. It appeared as though Lynn was filling the shoes of injured ace Adam Wainwright by improving slightly on what he had done in previous years. Lynn was pitching so well that FanGraphs writer Craig Edwards compared Lynn's career trajectory to that of Max Scherzer, who is probably one of the five best pitchers in all of baseball.

Unfortunately, Lynn has not been able to sustain his excellent start to the season. His 3.51 xFIP at the end of July suggested that he was due for at least some regression going forward, and it is true that his HR/FB rate since the beginning of August (14.6 percent) is more than double what it was prior to that point (6.0 percent). However, Lynn has seen a noticeable drop in the rest of his peripherals as well. Over his last eight starts, he has a 15.8 percent strikeout rate, an 11.4 percent walk rate, and an ugly 5.39 FIP. He also has a .341 BABIP over that stretch, which appears to be backed up by a decrease in soft contact and an increase in hard contact of about five percentage points each way.

While almost any pitcher can go through a bad eight-game stretch, it is quite concerning to see that Lynn's struggles do not appear to be caused by fluky luck-based factors. Numbers like this may cause people to wonder if fatigue and/or injuries could be having an impact. As it turns out, Lynn actually had an injury scare earlier in the season, when he spent a couple weeks on the disabled list with a forearm issue. According to Derrick Goold of the St. Louis Post-Dispatch, Lynn had experienced cramping in his forearm as far back as college, and it was something that he was used to dealing with.

Lynn spent just 17 days on the DL in the middle of June, and when he returned, he continued his solid run of pitching through the end of July. This success did not last long, though, which makes me wonder if Lynn's forearm issue could be a factor in his recent struggles. The good news is that nothing in Lynn's Brooks Baseball profile stands out as unusual. His pitch selection and release point seem to be in line with his early season norms, and his fastball velocity has actually increased throughout the season, even though it is down slightly from previous seasons.

However, Lynn's plate discipline numbers, courtesy of FanGraphs, are certainly more concerning.

The number that stands out the most is Lynn's Zone%, which has dropped by nearly four percentage points over the last two months. Lynn has always thrived on throwing pitches just outside the strike zone and getting hitters to chase, but over the last two months, he has thrown a dangerously low 37.2 percent of pitches in the strike zone. This may be the reason why hitters are swinging less overall and making more contact when they do swing.

This approach can also be very inefficient, leading to bloated pitch counts and shorter outings. This season, Lynn is in the top five among all MLB starters in pitches per inning (17.3) and pitches per plate appearance (4.04). Because of manager Mike Matheny's insistence on getting a high number of innings out of his starting pitchers, Lynn has averaged just over 100 pitches per start this season, despite having two abbreviated starts (one with 41 pitches, another with 59). In his 27 starts this season, Lynn has gone over the 100 pitch mark 17 times, and he has exceeded 110 pitches seven times. While many will claim that Lynn has the prototypical starter's build (he is listed at 6'5", 240 lbs) and is capable of shouldering an unusually large workload, I cannot help but wonder if Lynn's recent loss of command is a result of overuse and fatigue.

Ultimately, it is hard to know what exactly the Cardinals can do to help Lynn get back on track, besides getting him to throw more strikes. If his loss of command is indeed related to fatigue, then perhaps the Cardinals should look to skip his spot in the rotation once or twice before the playoffs. Then again, Lynn was recently critical of the Cardinals for giving him a start off after a minor ankle injury, according to Rick Hummel of the St. Louis Post-Dispatch. Lynn himself stated that "the extra rest didn't help. When you're in a rhythm and you're a creature of habit, the extra time is never good. That's just part of it."

If Lynn is not able to turn things around in his next few starts, the Cardinals may have to consider leaving him out of the playoff rotation entirely, assuming they make it past the wild card game. If the Cardinals' five starters are all healthy heading into October, a difficult decision will have to be made on which starter to move to the bullpen, since the Cardinals' other four starters (Jaime Garcia, Michael Wacha, Carlos Martinez, and John Lackey) have all had fine seasons. The thought of leaving Lynn out of the playoff rotation would have seemed ridiculous just a month ago, which is a testament to how well Lynn had pitched for much of the season. Nevertheless, Lynn's numbers have been trending in the wrong direction as of late, and the Cardinals should be legitimately concerned.

Nick Lampe is a contributor at Beyond the Box Score and Viva el Birdos. You can follow him on Twitter at @NickLampe1.