Tank Dell, Nico Collins and others are hindered by Stefon Diggs
The arrival of Diggs gives you a big-time receiver, but it also may give you a big-time prima donna. Diggs has made his past frustrations known quite well. He doesn't like sharing the spotlight as a receiver, and he wants to get the ball as much as possible. I prefer to believe that he wants to win that badly and that he believes in his talents that much, but regardless of the reason, he has made it clear he is to be fed the ball regularly.
To accommodate that level of attention, you have to take away from others. We already mentioned how it'll impact Joe Mixon, but Tank Dell and Nico Collins are likely to regress this season statistically due to Diggs' arrival. Now, that may not be a bad thing, if the team is producing on the field, individual stats won't really matter, but if the team is struggling to get Diggs the ball, then everyone is going to get upset.
Not only that but when you have two young players like Collins and Dell, you need to get them as many, if not more reps than others. More importantly, Collis is in a contract year, and Diggs may take away opportunities from him to showcase his skillset. Who knows how that affects his next contract and what the Texans are willing to give him?