Rondo may be our Carmelo in a sense but it's important to note that Carmelo has been a far more impactful player than Rondo has over the course of his career. If you can't come to that conclusion, you're smoking some serious green (see what I did there?).
Rondo can be the second or third best player on a contending squad. Carmelo can unquestionably be the first.
Except for the fact that Carmelo has never been the best player on a contending team. Rondo has.
No, he hasn't.
I take it back. Anthony was the best player on the 2009 Nuggets team that made the conference finals.
There is less of an argument to be made about Anthony and the WCF than Rondo and the ECF, or the Finals proper, I think.
BUT IF I HAD THE OPTION AND RIGHT PLAYERS AROUND... I WOULD RATHER HAVE RONDO ON MY TEAM 9/10 TIMES... WOULD YOU OF SWAPPED RONDO FOR MELO IN THE BIG 3 ERA?
This question is a little bit flippant regarding the main point here, which is that it's easier to build a contender around Melo as your best player than it is to build one around Rondo as a best player, but it's certainly an interesting question.
I would probably say yes because PP and KG are great passers. Even if we just had a facilitator at point like Jose Calderon, that'd probably be one of the best teams ever. Ray-PP-Melo-KG 2-5 is one heck of a Big Four.
2008 is still ends in a ring and I think 2010 would too. I think we would've closed out 2010 in six (the game Perk went down). We also would've gone further in 2011. I'm not sure about 2012, but in that fourth quarter of game 7 (vs. Miami in the ECFs) when the game slowed down, it would've been sweet to have two dominant iso scorers in Pierce and Melo.
I'm quoting myself here because I want to address the 2010 series vs. LAL. The concern here is we wouldn't have been able to match up defensively against their front court with Melo/KG.
Melo, like other scorers constantly scrutinized for their lack of effort on D, is clearly a capable defender at the very least. What people don't seem to realize is that these players don't have any extra "effort" to give, at least not over the course of an 82-100 game season (playoffs). They're carrying the majority of the offensive load and that takes enough of a toll on its own. Few players can give 100% on both ends every night and that's not because of below-average will, it's just that it takes intense will to do so night in, night out, every season. KG and Kobe come to mind, but even Kobe began slipping on D when he was asked to become
the guy on a title contender without Shaq (correct me if I'm wrong).
In a 7-game Finals series however, no drop of effort is left unsqueezed. I have to think Melo would be giving it his all just as he has in other big games/series (NCAA tourney, '09 Nuggets, etc.). If that's the case, his body is not all that different than David West's, except Melo is the superior athlete. Would people be scared to put West (Melo)-Hibbert (Garnett) up against Gasol/Bynum in that series? Perhaps, but the level of concern would be almost negligible.
Rebounding shouldn't even be a question. Melo is one of the best rebounding forwards in the game considering his workload on offense, PFs included. Obviously the advantage goes to Gasol/Bynum, but again, I'm not seeing the massively undersized (in terms of rebounding and defense) frontcourt that others seem to see when imagining Melo/Garnett. Don't forget that Pierce is also a big forward that can rebound the ball as well.
Our offense vs. theirs wouldn't even be close. Let's use Calderon as an example again. Calderon-Ray-Pierce-Melo-KG would have had the potential to be one of if not the greatest offensive starting lineup of all-time. Any slight disadvantages we'd face down low would be overridden by our offensive firepower.
At least, I think.

edit: Also consider that KG would probably have been top 3 in DPOY voting for about five straight years starting in 2008 if he could hand the majority of his offensive load over to Melo.