My recollection of what went on with Reinhart goes back to the summer after his second ELC year. After having been send back to Kootenay in his D+1 year, and having been told that he needed to work on is strength - which he did - he had a pretty nice rookie year in his D+2 season. - 23 G/19A/42 Points.
The next season he had another nice year - 17G/30A/47 Points . The summer after that second second ELC season, he was eligible to be extended. If I recall correctly, there was a lot of talk about that and how that is something that Reinhart wanted. He did come off of two pretty decent years. Perhaps the most notable thing about his play was that he had shown that he was not afraid to stay in front of the net - despite not being a physical player otherwise. He also had established a nice rapport with Eichel on ice and again, if I recall correctly, there was lots of talk that Eichel was a tough player to play along side so that rapport was viewed as a plus. In the end, while Eichel was extended with his the signing of his $10M deal, and several other players signed contracts - Reinhart was overlooked and would have to wait until after his ELC contract was done. My recollection is that Reinhart was disappointed that the Botts would not show faith in him.
The following off-season, coming off his best season yet (25G/25A/50 Points) - the feeling on the Reinhart side was that he would be signed to a long term deal, which is what he wanted. Again, base on my recollection, there were multiple signings of other players, leaving insufficient cap space for a long term deal. Botts ending signing him to the bridge/prove it deal pretty late in the game. That was again perceived by Reinhart as a slap in the face and pretty much set the tone for the chance of the Sabres signing him long term after that deal expired
So - I think that Botts bears the burden of having blown any chance of signing Sam long term in Buffalo.