After focusing on starting pitchers for the bulk of this series, it may be time to take a look at other elements of the game that can have an impact on your wagers. Starting pitchers are important and generally pitch 55 percent of the game or more, but the pitching matchups are always front and center and the oddsmakers have a good idea on how they’re going to line teams.

Instead of evaluating some starting pitchers due for regression, how about we shift gears and looks at some relievers and hitters that could be in line for a rough patch? You’ve seen all the stats that I cite regarding starting pitchers and regression. Things like comparing ERA to FIP, xFIP, and SIERA or looking at velocity changes, pitching repertoire changes, and the like. These are a little bit less reliable for bullpen pitchers because of sample size bias, but drops in velocity are much more noticeable and should be treated as major red flags.

We’ll start with hitters and what to look for there. One of the most under-utilized statistics in a hitter’s profile is ISO, which is short for isolated power. The formula is simple, Slugging Percentage minus Batting Average. For some hitters, their ISO is small because they’re contact hitters. Guys that have a very level swing plane and don’t generate a lot of power. For other hitters, their ISO is big because ISO is really a variation of slugging percentage. Slugging percentage, if you didn’t know, is (Total Bases / At Bats). Hitters will have a higher ISO if they are driving the ball for extra-base hits.

In terms of finding hitter injuries, ISO is one place to look. A player that isn’t driving the ball is either doing so because of a change in his approach that is stifling his power or simply isn’t driving the ball because of a strength issue, usually in the legs or the core.
Jason Kipnis is a prime example of this. Kipnis hurt his oblique on April 29 and missed nearly 30 days. Last season, Kipnis posted an ISO of .168. In April, his ISO was .160. Since his hurried return from the injury, his ISO is .037 over 100 at bats. Kipnis has seen ISO drops late in the season in both 2012 and 2013, but this one is far earlier and could probably be attributed to the oblique injury. It may be a case where Kipnis changed something in his approach to return faster or changed something to try and avoid injury again. Either way, something’s not right, and his performance has negatively affected the Indians.

Eric Hosmer is a great candidate for this exercise. After hitting 19, 14, and 17 home runs in his first three seasons, Hosmer has just four in 342 plate appearances. His ISO by season is .172, .127, .146, .104. His ISO drop coincides with a strikeout spike. He’s actually being thrown more fastballs and fewer sliders than in previous seasons, so his power drop cannot be attributed to being pitched differently. There’s a chance that there could be an underlying injury there for Hosmer and that’s worth watching with a Royals offense that isn’t exactly loaded.

Jayson Werth’s power is almost non-existent at this point. He went from a .214 ISO in 2013 to a .110 ISO so far this season. His slugging percentage has dropped 140 points this season. Werth was bothered by wrist injuries throughout the 2012 season. He dealt with biceps soreness in Spring Training and there could still be something to that. On a team like the Phillies, Werth’s power drop-off will get more and more noticeable. A healthy Chase Utley has been a godsend for that team, but the Phillies, who are a fade team the rest of the season anyway, are going to start to hurt more and more from Werth’s power outage.

The biggest player to watch for an ISO drop that could affect his team is Ryan Braun. Braun has experienced thumb issues and the precipitous decline in his ISO suggests that it’s flaring up again. Braun had a terrific .276 ISO in April, following by a solid .226 ISO in May. In June, his ISO has fallen to .134. To provide a frame of reference, players with .134 ISOs for the season are Xander Bogaerts, Nick Castellanos, and Desmond Jennings. The Brewers might be saved by all of the Cardinals injuries, but an unhealthy Braun in the middle of that lineup is going to make scoring runs difficult.

One relief pitcher to keep a close eye on is Joba Chamberlain of the Tigers. The Tigers have enormous bullpen issues and Chamberlain’s velocity has been bouncing around a bit. After only making 45 appearances last season and 49 combined Major League appearances in 2011-12, Chamberlain’s workload has been severely cut in the month of June. That may be a way to monitor him and manage him throughout the season or it may be a sign that he’s experienced some discomfort and has been scaled back.

Bettors need to monitor Dodgers closer Kenley Jansen. The huge workload Jansen experienced in April was severely cut back in May and has been cut back in June, but his velocity is down and his command seems to be wavering a bit. The control is still there, but the command is a little bit shaky. In the short-term, watch out for Jansen because he worked the 20th, 21st, 22nd, and 24th after just five appearances in the first 19 days of June.

While starting pitchers remain the most important part of the game to handicap, looking at relievers and major offensive contributors that are hurting is still important. The lines are comprised mostly of information about the starting pitchers, but knowing when key bats or relievers are limited or injured can make a real difference.