For the being a top defensive guy, he won't and shouldn't be asked of that with guys like Schenn, Aulie, Phaneuf and even Komi on the back end. Also even when Beauchemin was here for half of the second year his point totals weren't all that great. This during the time with the Grabo-Kuli-Mac line clicking as well.
As for developing, thanks to the acquisition of Liles he has another year in the 5-6 role to develop as Liles will take his spot in the top 4 and handle the PP duties.
You seem to be missing out on the very basic problem the Leafs have. They have 4 defencemen who can be shutdown guys, BUT NONE OF THEM CAN SUCCEED TOGETHER. This team needs a pair that they can send out against the other team's top units. That pair needs to be able to physically shut them down (we've got plenty of that) and move the puck north. We don't have a guy to do that. Beauchemin was that guy.
The Grabo line clicked all year, and they don't generate points from the D because Grabo/Kulemin are the catalysts and like to play high in the zone.
Liles replaces Kaberle's role, again, REALLY simple.
I'm not going to disagree that phaneuf has a fairly low hockey IQ (or poise as you've called it), but because of his physical attributes, he's able to rush the puck which I would say gives him some puck moving ability.
What I will disagree with however, is that Stajan would constitute any sort of upgrade on our centres, let alone a massive one. Stajan was ok and all, but he was nothing more than a 3rd line centre, easily replacable. So I really dont see how that could be the sticking point.
Also, there's no way you can say with any certainty that the reason Burke pulled the trigger on the deal was because of some short-sighted feeling of being upset with the team. I always thought he did it because an opportunity to grab a player with a high upside but inflated contract presented itself. That seems to be somewhat of his MO.
I really think you're getting too hung up on the cap hit aspect of things. Of any asset a hockey team like the leafs has at it's disposal, that's the most easily remedied.
The problem is -- Phaneuf's puck rushing is not the difference maker. He's good enough to do it when there's no pressure on, but that's irrelevant because when there's no pressure on, we're going to get the puck out of the zone regardless. What the Leafs need is a guy to play with Phaneuf that can get the puck out under duress. Beauchemin wasn't great at it, but he's far better than our options now.
You do realize that Stajan put up 55 points in his last full season as a leaf?
You do realize that Stajan was on his way to 60 points before being traded?
You do realize that we had at least 2 of Tim Brent, Darryl Boyce, Christian Hanson and John Mitchell in the lineup on most nights?
Stajan is at best a 2nd line centre, and when you're centres are a 2nd liner (Grabo), a 3rd liner (Bozak), and a couple of 4th liners / AHLers (Hanson, Mitchell, Boyce, Brent), adding a #2 centre is a massive upgrade no matter which way you slice it. Sure, you could argue that Stajan is overpaid at $3.5m, but Phaneuf's overpaid at $6.5m. At least Stajan would've satisfied a glaring hole in our roster last year.
Burke made the deal because he's an inept GM... what went through his head really doesn't matter.
There's too many other teams that have the full use of cap at their disposal to be wasting it.