I hate when benches and teams' depth is evaluated by listing out a lineup of 5 guys who aren't starters.
The Cavs have a fairly gross looking bench when you list it as Delly/Jones/Miller/Marion/TT.
Forget the playoffs, where using 10 guys is unheard of, when are you ever going to see the Cavs use a lineup of what I just listed in the regular season? You won't!
Benches, depth, however you want to refer to it, to me, is evaluated by how well it rounds out the team's talents and compliments what the core of the team is trying to do. The bench the Cavs have assemble does all of this extremely well except for the fact that they lack a rim-protecting big for situations where they need to do exactly that: defend the rim.
Delly compliments both of the starting guards extremely well. His skills match up with either guy, allowing Blatt to bring Delly in to play with either Kyrie or Dion whenever he wants. Delly's tremendous defensive ability makes this even more important. Delly isn't a better 'point guard' than Kirk Hinrich, but he fits this team and roster like a glove.
Mike Miller is a swingman, who, because of his passing ability and tremendous length, can excel at either wing position. He's one of the best shooters in the entire league as well as a very good rebounder for his position. He will almost exclusively be guarding the other team's lesser wing threat (I'll get to why). His role will be to knock down open shots, move the ball both in the half court and in transition, and rebound effectively, especially on the defensive glass. He will also be depended on to contest jumpers or cuts on defense.
James Jones fills the same role as Miller, though he doesn't fill it as well. I view Jones as injury insurance for Miller much as I now view Amundson as injury insurance for Andy and TT.
For his role, Mike Miller is almost perfect. For the Cavs, this is the role they need from him.
Shawn Marion was such a huge signing because he compliments Mike Miller AND Kevin Love AND helps spell LeBron for a few minutes on one side of the floor. Marion's defensive efficiencies offset Miller's aging defense while Miller's fantastic shooting offsets Marion's lack of spacing (I know Marion shot well last year, but I'm not expecting it to continue. If it does, gravy).
While Marion is on the floor, he'll be guarding the other team's best or second best scoring threat. He'll do very well at that while also helping out on the boards. His high basketball IQ will enable him to sift through open space for cuts, offensive rebounds, etc. By doing this he'll keeping his man honest on offense.
Next is TT, the new RCF whipping boy. TT excels at rebounding. What will the Cavs ask him to do off the bench? Yep. Rebound. TT is also a very capable man on man defender at the power forward position, and his quickness makes him a strong pick and roll defender. TT also runs the floor effectively in transition, which will shine even more if he's used as a small ball center. TT isn't very good at scoring points, but he no longer has to score a single point for his team to win games. Again, he's in a position where he should absolutely crush his new role.
As for Chicago, their bench is solid, but a bit redundant.
Hinrich is a strong, savvy backup point guard who's long out of his physical prime. He's a very effective shooter when open, but doesn't often create by getting into the lane. His defense is good when guys aren't blowing right past him. If Rose isn't in the game, Chicago lacks shot creators. Hinrich does not fill that role. If Rose and Hinrich play together, then Chicago is small and will give that up. I'd assume if Chicago plays those two together, Blatt answers by bringing in Miller at the 2 and having him guard Hinrich.
Taj Gibson is one of the best bench players in the NBA. Against the Cavs, it's unavoidable that he plays starters minutes if he doesn't start altogether. He's really their only defensive answer for Love, Marion, and a power forward-playing LeBron in a small lineup. Gibson is the Bulls' defensive specialist off the bench while also being able to score 12-14 a game. He's awesome, but he'll be working his ass off.
Nazr Mohammad has absolutely no place in this hypothetical series and I bet he won't be playing much all season anyway. He's old, slow, not very good, and out of place. The Cavs would be thrilled to run the ball down Chicago's throat with this guy on the floor. Who does he guard? What's he provide on offense?
I really like both McDourmott and Mirotic's games. However, they're both primarily stretch forwards who play little to no defense. I don't think they can be in the game together because of the points they'll be giving up. If they are in the game together, it means one of Gasol/Noah is out and one of Butler/Rose is out. I don't see consistent minutes for both of these guys, and whoever is better will certainly have an impact on Chicago's team because shooting is what they lack.
Tony Snell is also in a weird situation. Butler is going to play a ton of minutes, and Snell really serves the role of playing as a poor man's Butler. If he's coming off the bench, he's competing for minutes with both McDourmott (at small forward) and Hinrich (at guard). He's also an inefficient player with no ability to create shots for other players. He's a decent defender, but decent is going to get you anywhere when you have poor offensive skills.
TLDR: The Cavs' bench is comprised of role players who compliment the team perfectly and uniquely. They are not redundant and Griffin has done a superb job of assembling talent that fits together, just as he said he'd set out to do.