AJ Brown and Deebo are very similar players, I think, and I actually preferred Deebo as a potential fit for the Pats. I thought he'd be a better value too as he was projected to last deeper into 2nd round, while Brown was seen as a late 1st, early 2nd prospect.
With both on board for the 9ers pick, I guess value was no longer a factor but it came down to better projected fit in that offense. Very similar guys, wouldn't have gone wrong with either one.