Delly came into the league with 4 years of playing PG in college on a team that stressed ball movement and it still took a little while for him to get the ball moving right in the NBA. He came from a completely different situation. I'd sure like to see Sexton pick up some of his skills, but it is not fair to compare the two, even on their rookie year.
PG skills are not a "you got it or you don't" situation for rookies. There are many examples of late bloomers. Chauncy Billups is a great example of a "combo guard" (remember that term? seems dated now) who finally put the play making skills together around the age of 25. So it happens.
Seems like most of the guys who were late bloomers were the crafty guys with games that didn't depend on speed & quickness, but maybe that's just hind sight. Maybe they just stuck around when they were not as fast any more because they learned to be crafty. It seems foolish to think that Sexton can't grow his game just because he is quick.
Kyrie is an interesting example of how not to develop a PG. He showed great PG skills in college but when he came to the pros, he got fed a ton of minutes with weak team mates. I think he regressed as a play maker over the first couple years with the Cavs because he could get more glory using his handle, finishing and shooting skills. Then Lebron came and it got worse. Harder to find glory, less need to pass. I don't think Kyrie got back to being a PG until this season.
Will Sexton become a skilled player? I think there's a decent chance. He's got a lot of tools that are hard to teach like health, quickness and fight. We will know a lot more about what he is capable of in April.
Glad the Cavs got good role model for Sexton by bringing back Delly. Hard to think of anyone better than Delly. Low ego. Bucket of skills. Plays hard in practice. Still plays at a high level. Checks all the boxes. On top of that, he's Delly. Best possible player development move the team could have made.