Both McCarron and Garoppolo, to me at least, are only good as bridge type QB options. Which is why if I am the Browns I would not be willing to give up 2 first round picks to get Jimmy G. And it's why I'd be after a guy like McCarron.
Looking around the league right now and seeing what looks like a soon-to-be $14M signing of Glennon by the Bears, it's about affordability too in that bridge QB. Both of them do provide that.
We'll have to wait and see, as I know I am in the minority with my low expectations for Garoppolo. But I think he's a backup at best and New England knows it, which is why they're going to move him instead of Brady.