My totally unqualified opinion on how a team should be built is 5 starters, 4 backups. 3 reserve projects, 3 reserve vets. With each having specific characteristics. The raptors have a lot of imbalance in their lineup right now.
IMO, starers should be prototypical players for their position, not combo's or tweeners or "new style" players. Of course, if you have a versatile elite/all-star type player you may make an exception, however it makes it more difficult to build a winning team around an atypical player.
The raptors have a prototypical point guard in Calderon, they have two prototypical power forwards in Amir Johnson and Ed Davis. We'll give DeMar the benefit of the doubt as SG. And it looks like JV is the very model of a modern major league center.
So, let's say we have 4 of our 5 starters. Chosing between Ed and Amir is difficult, but Johnson is better player today. Now Bargnani is in some ways better that Johnson, but doesn't really do the typical work of a PF. Johnson and Kleiza can also play the 4, but are more combo forwards, not full time power forwards.
Since we don't have a starting caliber 3, we can assume one will brought in by way of trade/draft this off season.
So, that would give us the following starting 5:
Calderon, DeRozan, New SF, Amir Johnson, Jonas V.
A team should have 4 main rotation backups, each of them should be able to play multiple positions effectively. This is where you want your match up nightmares, new style players, etc, to give you different looks, between the 4 of them they should be able to hold down all 5 positions.
Bargnani is gold here, although primarily a 4, hey can play decent minutes at the 5, and even line up at the 3 in certain cases. May be tough for a former #1 pick to accept a backup role, but with one or maybe two rookies in the starting lineup and a fould-prone starting 4, there is no reason dude can't play 30 minutes of the bench.
Bayless is also nice, if he can play consistently off the bench, which he hasn't show. However, if he commits to this role, he can earn big minutes backing up the 1 and 2.
JJohnson or Linus Kleiza would be great as combo forwards backing up 3/4, but we don't need both of them. I'd go wil JJonson over Kleiza, although the Lithuanian connection with JV may give Linus the edge, also James probably has more trade value. So let's guess the team rolls with LK as the backup combo forward.
Now the team needs a backup swingman that can be a rotation player at the 2/3, the only guy we have is Gary Forbes.
so our rotation backups are:
Bargnani, Bayless, Kleiza, Forbes.
In your reserves you want a combination of projects who you may develop into legit players and vets who you can count on to fill in when injuries happen, or when projected young/rookie starters need to be bailed out and good locker room, unofficial assistant coach, tough practice players types.
I also think you especially need at least 1 prototypical center and 1 prototypical point guard among your reserves, that could potentially be starters if something goes wrong, obviously not great starters, but capable of holding the fort.
Aaron Gray is really good here, especially with a very young and unproven JV coming in, however Gray is probably a little to good and too young to be a deep bench player, so once Jonas comes into his own, Gray is probably on the block. However to start with it, it's prudent to keep him around.
Magliore is exactly the guy you need here, keep him in street clothes for now, when JV blossoms and Gray is moved, Jamal becomes the deep bench center.
The deep bench PG could be a project, maybe one of our draft picks, maybe European/international recruit or an undrafted player. If so, if this players blossoms, then you look at moving Calderon or Bayless. Otherwise, look for a vet minimum player for this spot.
The other three spots are available for vet minimum players, or other projects. Solo and one of our 2nd rounders probably takes two of these spots, with a training camp invitee grabbing the last spot.
So what does that leave us with?
Ed Davis and James Johnson have no real place on this team, unless they replace Amir Johnson and Kleiza. In any case we need to trade one of our spare 4s and one of our spare combo forwards.
In terms of the draft, we need either a starting SF, a project PG, and up to two deep bench prospects. Of our existing rotation players, there are plenty of weak links, not sure Amir is a real NBA starter, not sure DeRozan is either, so i'd definitely be into bringing in project players that can play 4 and 2 and see if get lucky with a draft sleeper. Of course we can't be sure about JV either, but he needs to be given the chance.
So our draft needs are, in order of priority, a 3 or 1 with the 1st rounder. If can't get one of these, then we need to trade the pick or trade the current backup or starter. If we do get a 1 then Bayless or Calderon is probably gone by the end of the season unless the player needs more time or is a bust, If don't get a 3 or a 1 in the first round, but get a 2 instead, then probably Bayless or DeRozan will gone. If the best player available is a 4, then Amir Johnson probably joins Davis on the trade market, unless we trade the pick.
So without any radical moves, our line up next year could be:
JV, AJohnson, New SF, DeRozan, Calderon, Bargnani, Bayless, Kleiza, Forbes
Gray, New PG, Magliore, Alabi, Some Young Dude, Some Old dude
So, we have JJohnson, Ed Davis and a number 8 pick, plus cap space to get a New SF, hopefully a current or future all-star caliber one. A deep bench PG who can hopefully at least contest for the backup job and have a chance of being our PG of the future, Some Young Dude who can either make Amir, DeMar or at least Forbes look over their shoulder, and Some Old Dude who can talk to Doug Smith when needed.