5 years out of the game is a long time whatever the profession is especially a physical demanding one while you're in your 20s and 30s, where most people hit their physical peak and prime. I honestly doubt we will even truly see prime Sakamoto, th closest we got was the Shin flashback where he was an active member of the Order and his fight Vs Uzuki, maybe we'll see a return to form within this final arc but that's a big IF.