Fractured back was building and crushed Rublev's early career at Monte Carlo 2018 in three set loss to Thiem.
Early 2018 hard court stats:
51.5% points won
42.6% return points won
60.5% serve points (really hurt by 42.4% 2nd serve points won)
Cincy onwards 2019 hard courts:
52.1% points won
only 39.0% on return
but 66.1% on serve including much improved 52.0% on 2nd serve (a long term liability)
Is he back? Maybe not with the drop from his superlative returning early in 2018 which featured great movement and consistency during that period. Getting his highest return game back and movement would have him near the top of the game. Recent Elo already 12 with recent Federer win pumping up the Elo.