I am going to predict that Doubs has more receptions than Watson on the season. I'm a bit more 50/50 on who has more more yards and TDs.
While clearly Watson has the upside to be better. I think Doubs is more polished to get more early looks. Watson just didn't have the route tree experience that Doubs has.
2011: Cobb: 25 receptions/375 yards/1 TD in his rookie year (Nelson, Jennings, Jones, Driver on the WR depth chart)
2014: Adams: 38/446/3 (Nelson, Cobb, Adams)
2015: Ty Montgomery: 15/136/2 (Cobb, Adams, Jones)
2018: MVS 38/581/2. (Adams, Cobb)
2018: EQS: 21/328/0 (Adams, Cobb)
2021: Amari Rodgers: 20/166/0 (Adams, Lazard, Cobb, MVS)
With a depth chart of Watkins, Cobb, Lazard, and Rodger (so far) in 2022, I think both WRs could put up 30-40 receptions and 400-500 yards.
Best case scenario has Watson put up MVS numbers (38/581) and Doubs at Adams numbers (38/466). But I have feeling Watson stuggles a bit more than Doubs with the full playbook; limiting his looks. He'll be the gadget guys and flashy distraction running deep routes while Doubs (and others) get the ball on the underneath routes. I'd guess Watson gives up an EQS-like start (21/328), but with a couple TDs.