Mike Pelfrey's bad 4th inning wasn't his fault, but he still needs to pitch better

At first glance, Mike Pelfrey's start against the Oakland Athletics on Tuesday wasn't any better than his three previous outings in a Tigers uniform. He allowed five runs on nine hits in six innings, resulting in his fourth loss of the season.

However, there are a couple of major caveats to the above paragraph. Pelfrey did not issue a walk on Tuesday, a stark improvement over the 12 walks he allowed in his first three starts. A small mechanical adjustment appears to be the reason for Pelfrey's improved command, and this type of performance -- plenty of hits, not many walks -- is more in line with what we expected from him heading into the season.

There were a couple of other reasons for the ugly score line, and not all of them were Pelfrey's fault. All of them came during a three-run fourth inning, so we'll focus our attention there.

Josh Reddick steals second base

After singling to lead off the inning, A's right fielder Josh Reddick took off for second base on a 2-1 count. Pelfrey's pitch missed high, but this helped Jarrod Saltalamacchia snap a quick throw down to second base. The throw was right on the money, but bounced away from Jose Iglesias' glove, giving a dead-to-rights Reddick his second stolen base of the season.

On the very next pitch, Lowrie singled to left field*, scoring Reddick. Had Iglesias made the play at second, Reddick is out and the game is still scoreless at this point. I don't want to dive too far into hypotheticals after this point, but one simple play at second leaves the Tigers with a 0-0 game and a man on first with one out.

*Lowrie's single glanced off of Jose Iglesias' glove, but Iglesias was playing up the middle on Lowrie in the first inning as well. It's a difficult play to make, especially if there is any spin on the ball going away from Iglesias, so it's not necessarily a given that this play gets made. If it had, we would have GIF'd the Iglesias highlight and praised him forever.

Coco Crisp hits a sacrifice fly

With runners on second and third base following a double down the left field line by Stephen Vogt -- we'll get to that -- a first-pitch-swinging Coco Crisp hit a routine fly ball to left field. Justin Upton had to take a step or two backward, but made the catch with his momentum going forward, allowing for a strong throw towards home plate in hopes of catching the tagging runner (Jed Lowrie) before he scored.

Instead, Upton's throw travels slightly off line, and is slightly higher than cutoff man Nick Castellanos would have liked. Castellanos jumps in an attempt to cut the throw and nab a tagging Vogt at third base, but can't make the catch. The A's local announcers opined whether Vogt would have made it to third base ahead of the throw, but the botched play -- Upton and Castellanos can share the blame here, if you're keeping score at home -- cost the Tigers another chance at an easy out.

Pelfrey allows four hits to left field

It's hard to pin everything from this inning on the defense when Pelfrey allowed four hits, including a pair of hard-hit balls from Reddick and Khris Davis. Davis' sharp single was the only real mistake of the inning, while the hits from Reddick, Lowrie, and Vogt all came on pitches on the outer half of the plate. In fact, Vogt's double was on a splitter that came in over a foot off the plate!

Here is a plot of all the balls put in play against Pelfrey in the fourth inning; the double should be fairly easy to identify.

Now, normally you could chalk this one up to bad luck, but look at how Pelfrey has used his fastball in 2016.

Pelfrey throws his two-seamer almost exclusively on the outer half, and doesn't look to challenge hitters inside all that often. Part of this is predetermined -- Pelfrey's two-seamer has heavy arm-side run, meaning it naturally tails towards that half of the plate. Part of this approach is because of the drastic difference in consequences. If he misses his spot on that half of the strike zone, the pitch is a ball outside. If he misses his spot on the glove side, it tails over the heart of the plate, which is especially dangerous against left-handed hitters.

Still, Pelfrey's predilection for the outside pitch was not lost on these A's hitters, and they were able to lean out over the plate and serve those pitches into left field. It's a great approach for them to have in this situation -- especially Vogt, who was in a two-strike count -- and gives other teams an easy starting point for solving Pelfrey in the future.

Pelfrey needs to pitch inside more often to keep hitters honest. He doesn't strike many hitters out, and doesn't throw his off-speed pitches often enough to keep hitters off balance. He found success later in the inning, working Yonder Alonso inside with his fastball. This induced a ground ball to the right side, where the Tigers were able to turn an inning-ending double play.

Conclusion: blame everyone

The Tigers theoretically could have gotten out of the fourth inning without allowing a run, but the way it unfolded highlights why sabermetric evaluation heavily favors pitchers with high strikeout rates. Weird stuff happen when the ball is put into play, and pitchers are often at the mercy of their defense (read: the baseball gods) if they aren't striking hitters out. This strategy can work if you have an elite defense behind you, but an average unit like Detroit's is still prone to the kind of ugly stretch we saw on Tuesday evening.