Rollins' OBP is .323, much more acceptable than Cozart's .264. Rollins was also an elite fielding SS in his prime. Not sure what he is today, and he might be a step slower than Cozart these days, but he still should be above average defensively.
Rollins also is much better #2 hitter than Cozart, and we know that's where both will be used.
Can't imagine either or both would cost any top prospects, but the money would be an issue.