Obviously, this thread has moved from a new feature feedback thread to a discussion on whether this should even be implemented, even though I've warned against this. I'm not happy about most of the posts here as they are neither on topic nor constructive.
The past few months, I feel like the BBs have cultivated an environment that encourages player feedback -- playerbase expansion discussions, the Utopia implementation debate, season feedback threads, BB activity on the forums, etc. Making a relatively minor and entirely technical change in the middle of the season and asking for player TESTING without OPINION is very odd. We're not the beta team or QA guys. You could have just posted a news article that it was happening and then checked the results yourself. If you didn't want opinions, I don't think you should open the lines of communication. It's not clear what other purpose this thread could serve.
It's not even clear to me where you're drawing the "constructive" line but here's my comment on this feature:
I like Blank lineups, but I do think they're too strong. I think it would be better to "buff" other options than "nerf" blank lineups. SFDC should be the best, but currently it has far too many problems (all-backup lineups on court, high stamina players ruining gameshape, injuries/foul outs totally destroying your rotation, etc.). I haven't played Hattrick much but don't they have a pretty well-thought-out substitution system? How about more features and more options instead of fewer? I've always wanted to make a team with a Nick Young / Jamal Crawford 6th-man shooter type off the bench, but it just doesn't work very well with the options provided.
Even if you plan on sticking to your guns and removing Blank, you're going about it the wrong way. The News post and this thread are very unclear about what's happening. How is the Blank lineup being prevented? What happens if you try to use one? It seems like you're creating a trap that will only frustrate users.
If you want to remove the feature, why let the lineup be submitted as Blank at all? You're talking about "countermeasures"?? Just put in some red text when you try to submit it that "Your coach doesn't understand this depth chart". At season rollover invalidate existing default lineups which may be set as blank and there you go, it's effectively extinct and you don't need player testing or this thread at all.