Put Baker at SS and leave him there !!!!!! CJ is an error waiting to happen.
Assuming your statement isn't ridiculous, (and for the record, it is completely ridiculous,) I'll humor you.
Baker is a 2B that was playing SS. IMO, if you're going to make any move, you put Baker at 2B; Marlow at 3B and move Boswell to SS.
OR, you could put McGuire at SS, but he hasn't been practicing there all year.
I don't think Baker has quite the arm to play SS everyday for a season. Therefore if you're planning for the future, (as you should be,) then you make the above moves.
Additionally, Baker has a fielding percentage of .939, (3 Es in 49 POs

CJ has a fielding percentage of .945, (11 Es in 111 POs) Baker is not really head and shoulders above CJ here.
And while you're at it, who you got replacing CJ's bat? As of late, all he's done is hit for the cycle as well as go 3/5 in Game 1 today. He's hitting as good or better than many on the team lately, (0.345 in the last 6 games.) Baker is not hitting well lately, (0.200 in his last 5 games) Not an easy flip of the switch like you're talking about.