Disagree with the first point, agree with the next two.
The Heat have been missing a huge chunk of their bench all season long with Haslem and Miller's injuries. Both really change the way the team looks when they are on the floor. The Heat took a few months to learn to play together (mostly figuring out how to use Wade) and Bosh took even longer to find his niche. As well as they are playing now, they can be better once Miller is fully healthy and once Bosh and Wade compliment each other better. Their defense is already at championship caliber level.
Rose has certainly regressed, though it might be from a combination of factors. His shooting percentages were on the decline as the season progressed. Pre All Star break he was shooting 45%, 36% on threes, 24.5 ppg, 8.2 assists and 4.4 boards. Post All Star break he shot 43%, 30% on threes (while taking more of them), 25.3ppg, 6.7 assists and 3.4 boards. In the postseason it is an even bigger dropoff despite the fact that Indiana and Atlanta aren't tough defensive teams. He is shooting 41%, 26% on threes (and taking even more of them), 28.2ppg, 8.0 assists and 4.3 boards.
I think Tibs put more pressure on him to carry the team later in the season as home court became a possibility to lock down. He looked to distribute the ball less, shot more threes and became a less efficient player. His legs are probably tired with Tibs pushing and pushing all regular season while other teams coasted in parts. If you listen to Tibs' comments on the team before game 3, it was pretty much "we need to put more effort in and work harder" which his team has echoed. Guess what? They are giving 100%, they just aren't being put in a position to win by their coach. Why can't they run real plays like they did earlier in the season? When you go back and watch the Bulls win over the Lakers in December they look like a completely different team on offense.
You are right about Deng not being a legit #2 option for a contender, but he should be #3 on the team and #4 ideally. Boozer should be the second option but he has been extremely shaky for them. Boozer can score, but he isn't a dangerous scorer. The other three teams left in the playoffs have a second guy who is a dangerous scorer (Jason Terry, Dwyane Wade and Russell Westbrook).
It is time for Tibs to throw out his junior high offensive playbook and get guys moving around and not just stand on the wings waiting for the ball to rotate over to them. This isn't the regular season and you can't pile up cheap wins against the Kings or Nets that way. This is deep into the playoffs and the teams left can play some serious defense. The Bulls need a serious counter to that and they just don't have one.