The coaching staff like Fountain a lot too don't they? GM likes Fountain too, heck he picked Fountain (the small school kid) before Cain.
Higher ceiling based on what? His college profile? What're these projections based on? We've seen many preseason star wideouts in Indy, every season there's one, what's Cain got over the competition?
Also the ACL tear seems to be underestimated. It's a lot to expect him to contribute seriously this year. Not many players can do what AP did. Look at Hooker last year, he admittedly wasn't same guy and took until this offseason for him to fully recover. It's just a huge ask to come back at full speed, and combining that with the fact he's essentially a rookie, I'm still not seeing how he's more of a lock than Fountain or Marcus Johnson or Pascal or Chester. Ideally, they all take jumps this year but if I were betting, I'd have Chester, Pascal and Fountain ahead of Cain for sure. Probably also Marcus Johnson. Cain's ahead of the rookies because he's been in the building a year but the others have actually been in live NFL (including playoff) games and contributed. I'd love to see Cain do well but ultimately I think he's behind the others and I think they'll all take leaps going into year 2 under Reich.
**not even mentioned Krishawn Hogan who the coaches reportedly adore.