Are we just going to ignore the difference between a declining Shaq and LeBron James in his prime (with a much older, much less assertive Dwyane Wade)?
The point is, MVPs are scorers. Obviously I didn't have to bring up Rose to make that point. Nash on the other hand proves you don't have to be a top scorer, you can do it with assists. The catch is, he was still arguably the best offensive player in the league. He did other things offensively than score and pass: he spaced the floor like Ray Allen, he drew lots of traps and double teams, and could draw the full attention of the defense from anywhere within 24 feet.
Now when it actually came to scoring, he's in a league of his own in terms of efficiency. Rondo looks like a D-leaguer in comparison and has no hope of ever even coming close. History tells us that elite rebounding and defense just doesn't make up for that.
If you're not taking enough attempts to be near the top of the league in scoring, you better be doing it better than almost everyone else if you want an MVP these days. It's 90% offense, and Rondo simply isn't a comparable offensive player to Nash in his prime.
Jason Kidd came very close to an MVP in 2002 (2nd to Duncan) averaging 14.7ppg, 9.9 apg, 7.3rpg, and 2.1spg, while shooting 39% fg, 32% 3pg, 81% ft. Rondo could put up very similar numbers but with a couple more assists and a couple less rebounds.
While a long shot, I don't think it's impossible, what I think it would take:
Close to a full season for Rondo (ideally 80+ games, but at least 75+).
60+ wins from the Celtics.
A flat season from LeBron and Durant (only 55-60 wins, about the same stats from last year with maybe a few small declines, like LeBron only averages 26/6/6, and Durant only puts up 27/7/4, etc.) Also a minor injury that keeps either out for 10-15 games also helps. Could happen. Especially if the LeBron/Heat aren't as motivated after winning it all, and maybe LeBron takes a few less shots to try to get a guy like Ray more involved, same with Durant if Westbrook/Haredn take a bigger role.
Several triple doubles and a lot of big time performances on nationally televised games. (Like Game 2 vs Miami, do something like that at least 3-4 times on TNT/ESPN/ABC during the season).
And if all that happens, and Rondo puts up for overall stats, something like 14ppg, 11apg, 5rpg, 2spg, 50%+ fg, 70%+ ft. I could see him finishing top 3, maybe even winning the whole thing.
But the stars have to be lined up perfectly, but everything I mentioned I think is possible of happening (Celtics winning, Rondo healthy, Heat and Thunder just being very good but not dominating, great stats from Rondo, and maybe with Ray out that happens, and status quo or slight declines from LeBron, and adding Ray maybe his stats dip).
Not outside the realm of possibility, but still not likely.
But while there are always exceptions, mgent is mostly right, 99 times out of 100, it takes a dominate offensive player. I remember the talk about how Ben Wallace was a potential MVP candidate during his and the Pistons prime, the best he ever finished in the voting was 7th with one measly 1st place vote. Kidd's the only other guy I can think of that wasn't the prototypical scoring machine that ever came close in the recent era. But it could still happen!