Comparing Gundogan's and Delph's injury record is flawed in more ways than just the quality of player. Gundo has had three entirely unrelated, serious injuries in his career, the first two he quite clearly recovered completely from, and with no reason to believe he won't completely recover from this one.
Delph has had niggles, pulls and tears to various body parts for a number of years. I rate Delph and really wanted him to make it here, I don't think he's ever disappointed and never looked out of place on the pitch, but as mentioned he isn't an absolute worldy to the point where you can mitigate his injury record. He needs to drop a level where he is first choice when fit, which in itself will probably improve his injury record with regular game time.