I think maybe you are thinking too much in an attacking sense.
Rose even when not 100% is still a bloody good defender, it's hard to think of a LB that is better in that regard.
Oh he's definitely not great in an attacking sense - he is good at getting the ball from defensive positions to the edge of opponents box,i'll definitely give him that,but the final pass/cross/shot is nowhere near good enough (wait until you see what Sessengnon can do).
But defensively i'd have him behind Jan (the best left back performance of the season in Dortmund) and Davies tbh, unless he's absolutely back to his best and can sustain that for a whole season.