I love both Ronnie and Ricky, but neither has any place in a top-5 RBs conversation at this point.
I disagree.
I'm not saying either one is necessarily top 5, just that they belong in the conversation. You guys are discounting them based on two things: Raw yardage this year. Lack of recent huge year.
Raw yardage is not a good comparison. Backs in a two-back system are going to get fewer yards. That's just the way it is and it doesn't speak to their quality.
Huge years are great, but also often the result of being the single focus of an offense. Not necessarily a good indicator of running back greatness.
The Dolphins also have a pretty mediocre bunch of run-blockers. There REALLY haven't been that many holes to run through for R&R this year. And blocking on the second level? Forget about it.
All that said, let's look at some statistics...
Ronnie and Ricky #4 and #6 in FootballOutsider's value-per-play metric. A much better metric than yards per carry or total yardage, in that it adjust for defense, garbage time -- and penalizes fumbles (whether lost or not). The latter hurts Ricky QUITE a bit, but that's fair. The fumbles SHOULD count against him.
Ronnie and Ricky are #12 and #5 in their TOTAL value metric, despite sharing carries. None of the four above Ricky share their load. The closest is Ray Rice, but Ronnie has 50% more carries than Willis McGahee. In fact, only a couple in the top 10 are in something approaching a dual-back system. Ricky really does stand out.
Ricky also scores very well on consistency -- in my opinion a very underrated quality in a back. He is third overall in "successful" runs. That is, runs that obtain significant yardage towards a first down (e.g. 9 yards on 3rd and 10 is NOT successful, 5 yards on 1st and 10 is).
The (other) top yardage backs are all boom-or-bust.
Sparano talks a lot about eliminating "negative plays". Well, that's what Ricky does well; he doesn't have nearly as many negative plays as the other top backs.
Ricky's problem (as was Ronnie's) is that they don't get the second level blocks which would allow them to rip off huge gains. And then there's the whole issue of defenses cheating up and not respecting Henne's deep ball

.
Want more traditional stats? Look at yards per carry. Ricky has an average of 4.8 yards per carry this year. Only 3 of the 13 backs with 1000+ yards have a better ypc.
Good enough for top 5 overall? Easy enough to argue, but maybe not. DEFINITELY deserves a place in the discussion, however.