I think he probably has one more shot at being a starter before his career begins the Wally Szczerbiak memorial tailspin.
Do you mean the 30 year old Wally who Hayward is already better than while clearly only being 70-80%?
Wally Szcerbiak's stats at 28 years old:
17.5pts 3.8rebs 3.2ast .476Fg% .393% .899 Ft%
Gordon Hayward's stats at 28 years old:
11.1pts 4.7rebs 3.6ast .425Fg% .327% .852Ft%
His numbers are actually a bit better than that, but they're still incomparable, because Wally's timeline is completely different to Hayward's.
Szcerbiak played 28 games in 03-04 averaging 22MPG. His numbers that year were roughly 10/3/1.
The next season, he went on to average 15.5/4/2.5 predominantly off the bench as well, however he averaged comfortably over 30MPG.
The next season he went back to the high 30MPG fringe All-Star level player he had been before Flip benched him.
Comparing Hayward right now to that Wally makes absolutely no sense. You're comparing a guy who had suffered a serious injury and had 2 seasons of working his way back into shape to a guy who is still in the process of getting back into shape.
What you really should be comparing is the Szcerbiak who came off the bench post-injury to the Hayward we have now, but that doesn't fit your Hayward-bashing agenda so you'll continue to ignore all context