I mean that Jan is a good footballer, like Vermaelen at the goons, but his defensive attributes aren't anything special. He's not very good in the air, he doesn't have very good recovery pace and is slow on the turn. He isn't a dominant centre-half in the way that Dawson is (at his best anyway) and he doesn't have the mobility or speed to be the man who can tidy up (King at his best, Kaboul at his best as examples). He is very good on the ball and good at bringing the ball out of defence, and I think his technical ability is above any of our other centre-backs. So that's what I mean.
If Lescott still has a bit of 'recovery speed', coupled with his ability in the air and his natural fit in the left-side (which Jan also has) then I think he could be a better partner for Dawson than Vertonghen is. I couldn't say that for sure though.
How is Chiriches rankes as our number 2 centre-half? He's had as many poor games as good ones and has two massive weaknesses as it stands: 1. He is weak in the air. 2. He struggles with passes played in between him and the left-back.
If Kaboul is fit and firing, he is the best centre-half we have. But it seems as if Kaboul is now crocked. If Kaboul could get back to what he was, then I think Vertonghen-Kaboul would make the best partnership.
Lescott--Dawson could be better than Vert--Dawson, but we'll see.
Maybe Sherwood sees Vert(footballer)-Daws(stopper) as his number 1 partnership, and then Lescott(stopper)--Chiriches(footballer) as the 2nd choice (with Kaboul pensioned off). And that'd make some sense, although still leaves us with some weaknesses to exploit.