Frattin was a fine player, when healthy, IMHO, as he was one of the few forwards who were able to beat guys one-on-one, and who drove to the net with the puck. But his numbers are average and, typically, a fine goaltender is much much more important to a team's ability to win games than a fine young forward.
In looking at the trade, Scrivens was a replaceable asset, and may very well have cleared waivers. He wasn't in RC's plans to get any legitimate ice-time.
A second-round pick rarely results in a game-changing, or even 2nd line player.
I think that Bernier is terrific in potentially upgrading the Leafs goaltending. And I think that the GM braintrust have concluded that if they can upgrade any position, especially goaltending, that they should do so, irrespective of the player's performances.
I believe that Reimer was absolutely terrific in Games 5 and 6 in the playoffs, and backstopped them to the wins. But he was more than just ordinary in the losses. The first OT goal scored on him was on the short side. His lack of any meaningful saves in the third period in Game 7 was, as we all know, tragic. (And of course it was a total team melt-down in the latter half of the third period in Game 7, but Reimer still didn`t come through when it was necessary for him to do so). In fact, looking at Reimer`s stats in the playoffs, he was 15th in GAA (2.87), and 10th in save percentage (9.23). But the games in which Boston won, he was extremely mediocre, if not substandard. In those 4 games, his save percentage was .886, and his GAA was 4.50.
Of course, statistics may be used in any context to justify any argument. I believe that Reimer`s performance in the playoffs may very well have justified the Leafs looking for an upgrade. And if looking at Reimer`s style, he clearly can`t handle the puck outside the crease, and has typically given up too many big rebounds, and his glove hand has not been stellar.
In conclusion, if Reimer does keep the starting job, it will be presumably based on merit over the preseason, and the start of the year. And if Bernier is the Number 1, then he has beaten out a pretty decent (but not great) young goaltender. And that can only benefit the Leafs in either scenario, IMHO.
(And finally we will have a patient GM who isn`t so keen to step up to a mike like Burke and declare the starting goaltender in the summer, without even seeing who is playing well going into the season).