Yet again, I am not saying Pietrangelo brings back Dobson+Walhstrom+1st. Bellows, Wilde and a 1st though? It's not "the top prospects" but it's 2 pretty legitimate prospects, and that offsets the 2nd pick Tampa sent over. Hell, I'm even fine if you want to top-10 protect that 1st for a year. But you're kidding yourself if you think Ishkakov, Salo and a conditional 1st is getting you a top-15 defenseman. At most, it would get get a long pause, followed by "tell you what, we'll think about it - if we're interested, we'll call you" and a no response after that even in the absence of an open declaration that Petro was on the market. It's sure as hell not getting you anywhere if Pietrangelo gets dangled around the league.
Howden wasn't a top prospect? No, he wasn't Foote or Point [and I wouldn't call Point a prospect after nearly 2 full seasons in the NHL at the time that trade was made] - but he was very highly regarded in the organization [generally 2nd to 5th depending on where you look]; he and Hajek were seen as a high price to pay but one the Lightning were willing to make for multiple Cup runs while the window is wide open. Claiming "well, it would be a mid-round pick, it would have more value than Tampa's unprotected 1st," ... well, if adding Pietrangelo doesn't make your team better, just say "we're no better off, I'm not interested." [Which would be laughable, but hey - everyone's entitled to an opinion, even if it's off base.
Besides, if your goal with such a trade is trying to win the Cup, do you really care if it ends up being 31st if it accomplishes the goal? Or, maybe you're just trying to be better than mediocre but not good enough to veer towards elite ... which is OK, I guess.
