Well - they certainly have been lacking an elite defender since... (ever?) unless you want to go back to Salming.
Phaneuf is a good dman - physical (although he will never be lay the big each game like Stevens, or like he did in the world jrs). He is overworked. And using this years stats - overpaid. Going to be hard to deal him, but is better off if he has a better defensive d-man to help him.
Gunnarsson - very capable, dependable dman - not a top pairing guy though - keep him. He would be a player the Leafs and their fans scratch their heads wondering why they traded him.
Franson - as much as he provides on the PP, defensively he is terrible. If a trading partner is there, do a deal. His only other asset to the Leafs aside from his PP points is he is their only R shot.
Gardiner - Has potential to be a top offensive dman, no denying he is one of the best skaters on the team. Again though - defensively he is nothing to get excited about. He is also pretty much redundant with Reilly's emergence. At his age, and with his potential he is expendable for the right deal.
Reilly - The reason why Gardiner and/or Franson are expendable. He is a stronger skater than Gardiner, better hockey sense, and shows a better compete level, as well as being better defensively. IMO - he will be better than Gardiner. Needs to be paired with a veteran defensive dman (which the Leafs sorely lack).
Ranger - was a feel good story who impressed in camp, but came out of the slow showing he hadn't played at that level in some time. As the season progressed he got better as his conditioning improved. Would be fine with him staying at a low $ value as a 6/7/8 dman.
Gleason - Came to Toronto hitting, blocking shots, playing physical. If he gets angry, is a tough guy to take on in a fight. Probably the toughest dman on the team right now. He may lack a bit in footspeed, but a new season may rejuvenate him. I would keep him as a veteran presence, bottom pairing player.
They cannot go into next season with these players and expect success.
As for Marlies players - hard to say, as most are only 1 or 2 year pros out of junior/college.
Percy showed how good he could be in pre-season, but needed the year in the "A", and his numbers show his transition has been smooth - is another year of AHL the way to go?
Grannberg - He is ready - he was touted as NHL ready when he came over, but as usual, the Leafs show little trust in letting him prove it right away when the big club lacked defensively. He isn't going to put up points, but has the chance to be a very good top 4 defender, plus he is a RH shot
Finn - will be a Marlie next year, not even in the conversation for making the Leafs
Holzer - is his chance at the NHL (in TOR) gone? He has been a very good dman with the Marlies, has a RH shot, and provides size. He may get one more shot next year
Brennan - certainly provides goals - however again not very good defensively - could be a good PP guy if Franson gets dealt, but his minutes should be sheltered otherwise.
One player that really intrigues me is MacWilliam - he showed his physical play in the pre-season, and put up good numbers for a defensive dman in the AHL (first pro season). He may need another year in the AHL, but being a US college player, is older, more experienced. This is the type of player the Leafs need in their top 6/7 D. Physical, hits hard, can fight - a much better skating Mark Frasor is what I see him as. Is he hurt? He has not played any playoff games yet.
Marshall also seems to be a MacWilliam type, maybe providing more offense.