Peralta is 12th in WAR in the NL. It's not really close. Even ignoring Skenes, try to find one way to have him better than Sanchez. Sanchez has a better ERA, better FIP, better xERA, and has pitched 15 more innings in 1 fewer start. Being a solid #1 is enough, we don't have to pretend Peralta is the best pitcher in the league when he would be the #4 on the Phillies.