Alright, here's an assessment.
The rotation
The ceiling is actually high. Sale, Rodriguez, Richards, & Eovaldi could stay healthy and regularly pitch quality starts, with Perez & Pivetta solid 4-5 starters. By year's end, it could be one of the best rotations in the majors.
The floor is abysmally low. Sale may never make it back this year with any effectiveness. Rodriguez could have aftereffects of his heart condition and never make it back this year beyond a few starts. Richards and Eovaldi could land on the DL for significant portions of the season. Perez and Pivetta, forced to pitch too many innings, could get exposed and shelled on a regular basis. Houck could be brought in to start but with only two pitches the league may catch up to him quick and outmatch him. It could truly be a disaster.
Ken's prediction: the rotation shows signs of success, but injuries and ineffectiveness plague it until the end of the season, when everything starts to come together, but alas it's too late to make the playoffs by then.
The bullpen
Ceiling: I think the most we can hope for is adequate.
Floor: While the relievers themselves aren't that bad, if the starting pitching gets shelled, the bullpen will get exposed and forced to pitch way too many innings.
Ken's prediction: As the starting pitching gets worse & worse, we get more and more bullpen starts, and the Red Sox find they can't hold a lead smaller than 4 runs by mid-summer. Again I think it gets better by year's end, but too late to save anything.
The offense
Ceiling: If JD Martinez and Andrew Benitendi regain their strokes, watch out American League.
Floor: I think the worst our offense can do is middle of the pack.
Ken's prediction: The offense starts out strong, but as the pitching bottoms out mid-summer, they start to feel like they have to score 10 runs a game and lose patience. Eventually the offense sputters as well. JD finds his stroke by year's end just as the starters start to keep us in games again, and the offense ends a respectable 5th in the AL.
Defense
Ceiling: err
Floor: Bad news bears
Ken's prediction: A struggle all year; we lose some games that are actually well pitched due to fielding errors, further adding to the offense's feeling like even 10 runs isn't enough.
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Overall: 80-82