Edelman was called a bust on Patriot forums by the negative types after year three, he was called injury prone and his "talent" and hands were questionable. He became one of the greatest crunch time players in franchise history.
Keene was injured all last or had a case of Foxboro flu, hardly an opportunity to showcase his skills. The only time we saw either of these guys was with Cam in 2020. According to a stat posted that season, Cam went to about midseason and hadn't thrown a single pass to his right, he perpetually missed TE's in the flat... didn't see them at all. He was the worst starting QB in the NFL.
Harry has been given every opportunity to play, wedged onto the roster, put on the field, thrown targets, he was also a first round pick and expected to contribute sooner... he is soft, he sucks, we know that definitely. Apples/oranges...
There are a million examples of rookies taking time to develop and becoming serviceable players by the end of their rookie deal. Not all rookies develop the same. Mike Vrabel didn't start a single game until BB traded for him in year five. No production is not the same as bad production and both of these 2020 rookies have great TE's in front of them on the depth chart. Something will have to happen in order for us to see them play, hopefully they rise to the occasion when that happens.