Devin Smith vs. Michael Gallup
Smith was a borderline 1st round talent, selected with the 5th pick of the 2nd round in 2015. Gallup was a solid 2nd-3rd round prospect, selected midway through the 3rd round because the depth at WR in the 2018 draft was excellent. Otherwise Gallup would likely have been a mid-late round 2nd round pick. Based on pure potential, Smith was ranked higher than Gallup at draft time.
But, Smith has missed so much time, that this year may as well be a 2nd rookie season for him. He hasn't had the time to mature into the position the way Gallup did last year and into this offseason. So, right now, Gallup should rank ahead of Smith. But Smith could well pull even with Gallup in the contest of who deserves to be the starter. However, Smith and Gallup are not the same type of WR. So it really comes down to who is a better scheme fit. I think the Cowboys will have to adjust their offensive game plans to better fit the skill set of Smith if he's the starter instead of Gallup. And Gallup may be a more polished route runner, and have a more expansive route tree than Smith right now - not that Smith doesn't have the ability to expand his route tree, but I'm not sure we know that yet.
This really comes down to coaching, IMO. Kellen Moore will need to adjust his gameplans to fit Smith or Gallup, depending on who is in the lineup. Smith adds a speed dimension that Gallup doesn't have, but Gallup may be more versatile overall. I think the Cowboys are blessed to have both of them, and having the option of using each to their benefit.
This will potentially accrue to the benefit of the team in the long run. Learning to adjust the game plan to fit Smith's skill set will allow them to discover what he does best. And then when Gallup comes back, instead of adjusting the play calls on a game by game basis, Moore will have the experience to adjust the plays called on a play-by-play basis, depending on who is on the field at any given time. That will be a good thing. If the Cowboys have a 2A and 2B option at the #2 WR spot, that just makes the team that much harder to defend for opponents.