Why the Phillies surprising rotation shift was the correct and only move Rob Thomson could make

With a regular season record of 95-67, the Philadelphia Phillies not only won the NL East comfortably, but they had the second-best record in the NL, allowing them to earn a first-round bye. Their postseason run will begin in the NLDS.

For much of Thursday's series finale between the New York Mets and Milwaukee Brewers, it felt safe to assume that their opponent would be the Brewers. This felt especially true after Milwaukee hit back-to-back home runs in the bottom of the seventh to take a 2-0 lead. Pete Alonso and Co. would have none of it, though, as New York stormed back in the ninth inning to take a 4-2 lead which they would not relinquish.

The Mets winning this game set up what should be a dramatic series between these two NL East rivals.

The fact that New York had to play in the Wild Card Series while the Phillies moved on automatically thanks to their bye meant not only that the Phillies would have home-field advantage in the NLDS, but it also meant that they could set their rotation up however they wanted while the Mets would have to figure it out on the fly.

Their ace, and the pitcher most would pick to take the ball in a postseason start, Zack Wheeler, will take the ball in Game 1 looking to give the Phillies the early-series advantage. In prior postseasons, the Phillies would turn to Aaron Nola, an All-Star starter in his own right, to pitch in Game 2. This season, however, will be different, as the Phillies revealed that Cristopher Sanchez will be taking the ball. As weird as that might sound, it was the right move for Rob Thomson to make.

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Phillies make surprising, but correct shift to their postseason rotation

The decision to start Sanchez over Nola in Game 2 came down to one thing - having Sanchez pitch where he is most comfortable.

Sanchez had a great year overall, posting a 3.32 ERA in 31 starts and even earning a midseason contract extension, etching himself in Philadelphia's rotation plans for years to come. He'd be a No. 2 starter for many teams with how good of a season he had, but with Nola in the mix, Sanchez is comfortably their third-best pitcher at best right now.

His overall numbers were excellent, but a deeper dive into his statistics from this season reveals one eye-popping factor. He is untouchable pitching at Citizens Bank Park, the home of the Phillies, and is not good at all pitching on the road. The numbers show just that.

Sanchez made 17 starts in South Philly, posting a 2.21 ERA in 110 innings pitched. He had 99 strikeouts compared to just 17 walks, allowing only six home runs. These numbers are pretty incredible considering the fact that Citizens Bank Park is one of the most hitter-friendly parks in the majors.

Sanchez's 2.21 ERA at home ranked fifth among qualified starters, better than NL Cy Young frontrunner Chris Sale, and even better than Wheeler's. His road numbers revealed a whole other story.

The southpaw had a 5.02 ERA in 14 road starts, covering just 71.2 innings. He had only 54 strikeouts compared to 27 walks, and allowed five home runs. He didn't pitch as much on the road as he did at home, yet he issued 10 more free passes away from home than at Citizens Bank Park. That is alarming.

Sanchez had one of the best seasons in the majors pitching at home, and had the 10th-worst ERA pitching on the road. These kind of splits are hard to fathom and are something Sanchez is going to have to figure out, but when the Phillies can line up their rotation however they'd like to, why not use Sanchez at a ballpark where he's dominant?

Nola is a veteran who, while he's better at home than on the road, has splits that aren't nearly as dramatic. He also happens to have a solid 3.28 ERA in 14 career starts at Citi Field, including a complete-game four-hit shutout in Queens this season. Sanchez has not had nearly as much luck in New York.

Citi Field will likely be a madhouse on Tuesday, especially if the Mets can find a way to steal a game on the road. The Phillies know that, and are using Sanchez in Game 2 because of that. Thomson isn't saying Sanchez is ahead of Nola in their pecking order. He's simply putting his pitchers in the best possible position to succeed.

With how dominant Sanchez is at home and how awful he's been on the road, using the southpaw in Games 3 or 4 on the road wouldn't have made any sense when the Phillies could order their rotation however they please.