Really don't want to go down the whole Mancini rabbit hole again but I insist that what happens to a player post-Inter is largely irrelevant - or at the very least, not as relevant, compared to how they played while here. That is the criteria we should work with.
Fact is, Ljajic had some great, great games for us and was a leader on the pitch. We didn't see any kind of the petulance from his Fiorentina days, and he was just 24 years old and something like €9-11m to redeem. We spent more than that on a 29 year old Eder who, in addition to having a very mediocre Inter career after a horrid first 6 months, deprived us of Ljajic's creativity, technique and the fluidity he provided. And replaced that with Eder's great.. running? Diving?
Same goes for Telles. Who cares what he did after he left. For that matter he's actually doing great at Porto by all accounts. But he was very solid here, 2nd on my list (after Cancelo) for best performing fullbacks since Maicon. Like Ljajic, he was young and cheap, but instead we blew money on others like Erkin, Santon and Ansaldi who combined, had less good games than Telles in his short Inter career.
If a player plays well here for a season, and his loan is redeemed, you generally have to rely on them to continue that level of performance. That is after all, why you redeem them. If Ljajic couldn't reach those levels again at Torino, sure, that's on him. But it really doesn't detract from the concept that A) he performed well here and B) if he was redeemed, we could have arguably expected him to continue performing well.