Rick Porcello should be starting Thursday against Nationals, not Doug Fister

With two off days built into the Tigers' schedule this week, Jim Leyland announced last weekend that Rick Porcello would pitch out of the bullpen during the two-game series against the Washington Nationals. His next scheduled start would then be Sunday, May 12th against the Cleveland Indians.

At first glance, the decision makes sense. Doug Fister, originally scheduled to start on Wednesday, would make his start on normal rest. After last night's rain delay, he will start on an extra day's rest on Thursday afternoon. Max Scherzer and Justin Verlander, due to pitch on Friday and Saturday, would also make their respective starts on an extra day's rest. Porcello was effective in his lone relief appearance of the season, pitching two perfect innings against the Oakland Athletics on April 14th.

That said, I don't think that the Tigers made the correct decision in this situation for a number of reasons.

For one, Porcello's outing immediately after his relief appearance didn't go so well. He allowed nine runs in 2/3 of an inning against the Los Angeles Angels, a game that most of us would like to forget. Whether the long layoff between starts had anything to do with this isn't clear, but it's worth noting that Leyland described Porcello's performance as "rusty."

The next reason Porcello shouldn't be skipped -- and this is the big one -- is the team he will be facing. The Nationals are 27th in the majors in runs scored, ranking above only the Marlins, White Sox, and Dodgers. They also rank 28th in on-base percentage, 23rd in slugging percentage, and 27th in wOBA. Even with Bryce Harper's hot start, they have struggled to score runs. Considering that Harper has been limited by a bruised rib over the last week or so, it seems like the Nats were a perfect opponent for Porcello to face.

Meanwhile, the Indians have been anything but cold at the plate. Going into last night's action, they were eighth in the majors in runs scored, fifth in on-base percentage, and first in slugging percentage. They were also tied with the Atlanta Braves with 44 home runs, the most in the majors. They are 8-1 in their last nine games and have scored 63 runs in that span, an impressive seven runs per game.

As fate would have it, Porcello has been particularly homer prone to start off the 2013 season. He has the second-highest home run rate on the team behind Brayan Villarreal and is the only starter to allow more than three home runs this year. Fister has only allowed one home run in his first six starts, and has never allowed more than 15 dingers in a season. Porcello's career low is 16 home runs allowed.

If you read just about anything Patrick wrote about Porcello last season, you would know that he had some awful splits against left-handed hitters. Lefties hit .325/.381/.503 with 11 home runs off him in 2012. Those splits have reversed themselves so far in 2013, but I imagine that we will see this trend revert to normal by the end of the year. Porcello has allowed an .819 OPS to lefties throughout his career. The Nationals feature the most dangerous left-handed hitter between the two teams in question, but will only start four lefties on any given day. On the other hand, the Indians could field a lineup featuring as many as seven switch-hitters and lefties if Michael Bourn returns from his rehab assignment this weekend.

Fister's splits, meanwhile, aren't as pronounced as Porcello's. He allowed lefties to hit .270/.300/.434 last season, but also struck them out at a 21% clip. He also has the same excellent reverse splits against lefties that Porcello has this season*. This is nothing few for Fister, who has struck out 17.4% of the lefties he has faced throughout his career.

*I wonder if this has anything to do with facing the Houston Astros? We might have to look into this.

Additionally, Fister has owned the Indians throughout his career. He only has a 5-3 record to show for it, but his peripheral stats point toward total domination. Case in point: he has a 2.24 ERA, 0.896 WHIP, and 63 tOPS+ against the Tribe in 12 career starts. Porcello hasn't been bad against the Indians, featuring the same 5-3 career record against them. His 4.10 ERA and 1.366 WHIP against them are better than his overall career numbers. However, he 0-2 with a 5.17 ERA, 2.043 WHIP, and 142 tOPS+ against Cleveland last season.

Porcello has never faced the Nationals in his career, while Fister allowed one run in eight innings against them as a member of the Seattle Mariners in 2011. Naturally, he was left with a no-decision.

Looking ahead, the Tigers' schedule doesn't provide any advantage or disadvantage to pushing Porcello's start back. If he were to start on Thursday, his next start would be against the Houston Astros. However, both pitchers will face the Texas Rangers, Minnesota Twins, and Pittsburgh Pirates in the coming weeks, with Porcello scheduled to face the Baltimore Orioles at Camden Yards on June 2nd. Here are their next four opponents as currently scheduled.

Projecting anything after that gets a little shaky with a couple more off days mixed in.

One last thing that the Tigers have to consider when deciding to skip Porcello is whether they are taking their other starters out of a rhythm by giving them an extra day of rest. In this case, Fister, Scherzer, and Verlander would all be pitching on six days' rest instead of five -- which is already an extra day of rest -- if Porcello were to start against Washington on Thursday. Of the three, only Scherzer has shown a significant drop in performance when given six or more days of rest during his career.

All things considered, I don't think that the small chance of taking these three out of their rhythm is worth the risk of having Porcello pitch against the Indians. The stats all point towards Porcello having a huge disadvantage against the Tribe before he even takes the mound. When you consider the relative importance of beating a divisional rival, the decision to skip Porcello doesn't make much sense.