In addition to the non-reinforce and sail out of the Baltic fleet, you need to look at the Med Fleet too Frimmel. An AC buy for the Med looks good… on paper.
Yes, it secured the Med… for a turn.
After that, US parked a fleet of an AC, FIG, 2 DSTs and TRN’s in SZ12 and blocked you in. Added a BOM in Africa that would add serious punch to an attack on your fleet if you left it in range of that US fleet. That left you with just Africa landings or RUssia support as the roll for that Med Fleet, and in either case, the fleet was too far east to shield Southern (run the sim on a Southern attack by USA in US3… 2 INF, 2 ART, 1 FIG, 1 BOM against 6 INF and an AA… 74% Allied win…)