Da Costa: we still don't know how he would have fared in the NHL. Never got a chance to prove himself here. The last time he played here he was pretty good, then he was sent down never to be seen again. Doing well in the KHL is no guarantee, but what else he can do to prove his worth, play badly there?
Condra: major PK contributor (along with Gryba, probably). Compare our PK before and after Condra. In his case though, I realize the contract he got was probably too much for what he did for us, and given our budget constraints I can understand letting him go. Cameron was a fan anyway, so he can't be blamed for anything concerning him.
Prince: maybe he didn't have the impact we hoped he would on our team, but dude had a great pedigree, and he provided skills we are dearly lacking. Never really put in a position to succeed. We'll see how he turns out in the long term, and maybe he won't be much, but it's legitimate for some fans to be upset, and more importantly treating them sarcasm and mockery is what gets me.
Prince and Da Costa both had play-making and puck-handling skills, and I think these skills were undervalued by our previous regime (compared to, say, "grit"). That's the symptom part I was referring to.
DaCosta: The best you can say for DaCosta is that maybe if he got more opportunity, he might be an NHL player. Other teams haven't seen enough from him to try and entice him out of the KHL, so I'm inclined to side with the Sens evaluation until proven otherwise.
Condra: Yes, he was a big contributor on our PK, and this year's PK sucked. The problem is Condra doesn't do enough to make his new team want to keep him in the lineup either, so did we really do a poor job in evaluating him? This years PK failed because of the guys we had replace Condra on the PK (Chiasson, Pageau, Lazar, and Zibanejad) lacked experience big time, not because Condra was some supremely good penalty killer. Pageau, Lazar and Zibanejad are all young and will improve. Chiasson likely leaves the team. I also believe coaching was an issue in this regard. If this coming season, the PK rebounds to close to league average, you can safely assume that Condra wasn't the be all an end all of our PK. Suffice it to say, there is way too little evidence to say we incorrectly evaluated Condra. You can certainly suggest that we didn't properly assess the guys replacing him, but to be fair, they expected a healthy MacArthur, Turris and Michalek to be available, the last one in particular was expected to be a regular on the PK but was injured to frequently to make any significant impact.
Prince: Time will tell. I don't see him ever becoming a top 6 guy, but I'd love him to prove me wrong, I was really high on the pick. I think it's unfair to say he never got a chance though. He played about 180 mins combined with one of Turris or Zibanejad, which is a decent trial run for a rookie in the top 6. By comparison, Dzingel got 100 mins combined with Turris, Zibanejad and Pageau(who I've included because he took over top 6 duties when Turris came out of the lineup). Now, Dzingel only played 30 games, but even prorating that to the 42 Prince played, you end up with less top 6 mins, but Dzingel looked more comfortable in that role than Prince ever did imo.