one of the best posters on this entire board should know when players are in position - and who keeps them there. jones ain't that guy. polamalu as an example will embarrass anyone - especially clark. he's an exception to the rule.
jones plays stiff and likes to roam. let him do that. clemons plays much more more 'smooth' than jones in terms of being in position - play towards their strengths IMO. jones might succeed from a great defense but will never reach his potential as a FS. meh.
I would disagree that Clemons is any smoother than Jones. Both are basically tugboats in their change of direction, which is why they're playing FS instead of corner. Their COD numbers from the combine are pretty awful and they show it on the field.
I guess it comes down to what you view as "ideal" in the position. My vision for a FS is a player with great instincts, intelligence and ball skills. Speed and change of direction are secondary to an ability to take great angles of pursuit to the ball carrier and/or the ball once you have changed direction. My vision for a strong safety is someone who is comfortable (physical enough) playing the box but also who can cover tight ends and running backs man to man. Ideally this is a versatile player with the athleticism to play multiple roles in a pinch (whereas a FS is generally back in single high or two deep), who is quick reacting in small spaces. The special package defenses the Packers run with Charles Woodson are an example of the role you ideally want your strong safety to be able to play at times, as they take advantage of Woodson's ability to play physical at the line of scrimmage (for a corner) to enable him to cover or blitz and confuse an offense with his versatility.
Remember when Sean Smith was playing that sort of "rover" role early in the season last year, covering tight ends and backs? Well, that was Yeremiah Bell's old role from the two previous years. Bell would come down into the box and cover people in short zones or in man to man (playing where an athletic linebacker would generally play) and Tyrone Culver would come into to play 2 deep with Gibril Wilson or Renaldo Hill. It's not a coincidence that's the role they had Bell play, nor that they thought Sean Smith would be good in that role (with Bell remaining back at SS). The man to man and short zone coverage responsibility requires certain skills. Bell has them. So does Smith (obviously, you give up some physicality there relative to Bell and especially relative to a linebacker, who relies on his size and strength to overcome his short comings in coverage in that role. But you gain a lot of coverage ability and also height, which is an underrated attribute to have in your short zone players). Clemons and Jones, in my opinion, do not have these skills. They can't cover man to man. They just can't. And their stiffness would be exposed close to the line of scrimmage.
With all that said, however, the truth is that in the modern NFL, the roles of these two players have become somewhat blurred. Last season the Dolphins had Clemons up at the line and Bell back in the deep middle every once in a while. More and more teams are playing more and more cover 2. The Dolphins play less than most, I would say (having not run the numbers), which makes the debate more relevant here than it would if we were discussing the Colts or the Vikings, for example. But still, in many ways these roles are interchangeable, especially if you don't mind restricting the roles these guys play. I've said before and would repeat here than I think Jones'
best fit is with a base cover 2 team. That's really where he would excel, imo. Plus, I think he needs to work on his pursuit angles, as they're spotty at times, mostly due to over aggressiveness, imo (Clemons probably takes better angles, but doesn't always).
The bottom line is I don't think either guy is set to become a star. But I do think that the best bet for both players is FS. It would surprise me, were Yeremiah Bell to get hurt, to see either of them move over and play his spot. That job would almost certainly go to Tyrone Culver.