A fit Luke Shaw is the best LCB at the club and it's not even close, has the physical aspects that Martinez doesn't.
But you are talking about the player Shaw was 2 years ago, if we just start knocking 2 years off every player to make an argument it becomes so far removed from reality it's irrelevant.
Shaw today hasn't be able to stay fit for more than 10 minutes, he is useless and shouldn't be in any plans for next season.