By that logic, almost NO pick deserves "flack".
I don't think my logic brings you to that conclusion, but I agree far fewer picks deserve flack than receive flack. We should expect NFL scouts and GMs to be excellent talent evaluators, and should have top notch draft strategies. But they shouldn't be expected to own crystal balls.
I think it's hard for us to know which picks deserve flack and why. We don't have access to as much information as NFL scouting departments, and even if we did we're not necessarily competent to second-guess their actual scouting analyses. In some cases, e.g., Lawrence Phillips, it's not so hard to second-guess the pros because the concerns about the player were evident even to non-experts. In other cases, like maybe Andre Wadsworth or someone, if the signs of busting were there they were hard for a lay person to see, so it's hard to know how blameworthy the Cards were.There are two questions here with Charles Rogers.
1. Were the signs of busting evident? I know someone who was at MSU at the time and said that it was generally "known" (i.e., rumored) that he did lots of coke. Combine that with the fact that he failed the drug test and maybe the signs were there. It's arguable, at least.
2. Even if the signs weren't sufficient to present a grave concern, does that mean his character was on par with Calvin Johnson's? I don't see how anyone can answer affirmatively with a straight face. I can't find the quote now, but I saw one scout/commentator (I think it was John Murphy, but it could have been Mike Mayock or Pat Kirwin or someone else) say that CJ gets the highest grade in character that they've ever given. There are whole articles written about his great character.
link1,
link2,
link3. The comparison to Charles Rogers in that respect makes no sense to me.
Also, while perhaps an argument can be made that we couldn't have known about Rogers' character concerns ahead of time (although I disagree), some people in this thread have gone farther and suggested even in hindsight that Rogers' character wasn't the reason for his failure (attributing it instead to injury). As another poster correctly pointed out, however, Rogers' collar bone isn't the reason he is running a 4.9.