I think people are getting overly excited about Tillman making 1 shot. I see Tillman as the better substitute for Porzingis than Kornet in this series, but there is a huge drop off when Horford comes out and Tillman goes in. He is a career 27% 3Pt shooter. If he is playing, DAL is going to leave him open and hope he shoots.
Since Horford can't play the whole game, we are going to need to play someone. Playing Tillman in that role is fine, again, a little better than Kornet vs. DAL. I like Tillman. I hope he comes back. He is a useful enough bench guy. I think he has the potential to be more at the Pritchard/Hauser level in terms of rotation minutes. But I see that as his ceiling.
Tillman mostly brings nothing on offense. He hit that three but he's a bad 3 point shooter and doesn't have much of an offensive game at 25. I do think he has the same amount of points as Pritchard in the series... Tillman's value is that he can guard 1-5. He's also a really good match up on Luka. Luka is used to being stronger than the guys that are guarding him but Tillman is big and strong and can move his feet and hold his ground.
I don't disagree with most of what you are saying but you are implying that Pritchard is no better offensively than Tillman. Yes, Pritchard is 1-13 in the finals. This moment is clearly too big for him. But he is a far better offensive player than Tillman.
It is true that Tillman is a solid, versatile defensive player, more so than Kornet. That part of his game is at the level of a regular rotation guy. But offensively, he creates a dead spot in the flow, at least that has been the case since he got here. That is why he hasn't played in the playoffs/finals, except when we have no other option. I would not play him any differently.
I think if he gets another season with BOS, he will improve or be able to better integrate his game in to the overall team. It is not easy to come into an established, high level team like Boston, in the middle of the season. That doesn't mean he has to start making 3s. That would be great, but there are other ways. But the finals is not the time to be trying to figure that out.