You are exactly right, and there are more problems than that at tackle.
Carey is unproven at LT and struggled there his rookie season. Shelton was a disaster at LT last year and now they are hoping he can play RT, we'll see.
Toledo can't stay healthy long enough to play, Alibi is still hurt, and Rosenthal has been slowed by injuries his last few years. That leaves Julius Wilson and Marion Dukes, both undrafted rookies, possibly trying to play the other tackle spot. I thought our draft was pretty good, and we have serious depth at OC and OG now, but not a lot of help at tackle. This is going to be the Dolphins achilles heel all season.
GO PHINS~!