Of course you have no way of knowing how badly they would have struggled at LT, the RTs are guys that don't project well at LT at the NFL level
What are you basing this on? All three top tackles taken in the draft last year were moved to RT with the thought that they would eventually move back to LT. Otherwise they wouldn't have been taken top 10. Two of them will presumably be doing so this season. Some of the other LTs taken in the first round and moved to RT mentioned in the article eventually moved to LT and found success.
but you can clearly see around the league that college LTs do transfer to NFL RTs, due to the amount of RTs in the NFL that were LTs in college.
What is that amount?
I'm not sure immediate success has much to do with anything, the players mentioned, all the guys who played at LT were the higher rated guys, so did they have more success based on that.
Again, the top three guys last year were highly rated, moved to RT, and sucked.
As far as immediate success, the author of the article is looking at it from the perspective that the Dolphins need a guy that can come right in and play RT and upgrade the position. The Dolphins cannot afford to have an RT come in and give up a lot of sacks and pressures.