The same Delph who was a reasonably priced squad player who at first did a u-turn. Did alright but not in his natural position. Fernando was just as good but both were not quite good enough going forwards.
Not sure on your point to be fair? Delph did more than 'alright' in the 17/18 record-breaking season at left back. He was never good enough to play midfield for us under Pep, it was a struggle under Pellegrini as you alluded to.
Grealish is a cut above Delph and that's just obvious.