There is a reason for it. With Whit it was age. Smith I think is even better than Whit in pass pro. He's as good of a lockdown tackle as you can get on the blindside when he's healthy.
Which is why he's hitting the market, that health. But let's say the Rams sign him in FA and we enter the playoffs with that dude on the blindside... Stafford will be positioned to make a serious run. The OL would look very good with Jackson at RG, as he and Hav would overpower teams in the run game. Only thing they'd need is to draft a center.
So vs a plan where they draft a LT at 19 this would allow them to grab an impact defender up top. Which I like the idea of very much. I really want defense to get an impact player or two and using that top pick is a nice way to increase odds of that happening.