Nick Pivetta
Boston's pitching staff doesn't have a shortage of guys that have warts with the injury concerns of James Paxton and Chris Sale leading the way. However, there is basically no chance of Boston just eating the $27.5 million owed to Sale next season especially if he continues to pitch well now that he is back from his latest injury. Instead, the easiest place to upgrade in the rotation going into 2024 may be the spot currently occupied by Nick Pivetta.
Oddly enough, Pivetta was perfectly reasonable as a reliever for the Red Sox and it would be very defensible if Boston wanted to move him back there in 2024. However, Pivetta really struggles the second (or more) time through a lineup as his command problems and issues with the long ball become amplified the longer he is in games. This is a guy with good stuff, so perhaps just sticking to making him a reliever is the best play. In any case, he probably doesn't need to be in the rotation next season.
Chris Murphy
It probably isn't talked about enough that the Red Sox have a top 4 bullpen by fWAR in the American League this season. Kenley Jansen, Chris Martin, and the aforementioned Pivetta have been really good in relief for Boston this season with several other guys chipping in as well. However, one bullpen arm that probably needs a hard look after this season is lefty Chris Murphy.
On the surface, Murphy does not seem like a guy that should be a candidate for a roster culling as he has posted a 2.94 ERA this season and boasts a very reasonable 9.09 K/9 rate. However, a closer look points to trouble brewing as his more than four walks per nine innings pitched in the big leagues is actually a modest improvement over what he was posting in the high minors. His breaking balls are weapons to be sure, but his fastball is a bit suspect and his command is spooky enough to make one think really hard about whether or not Boston wants to take their chances on him in the bullpen in 2024.