[Trump Echo]

IMO, the average player on BBO doesn't know what they're doing, even if they think they do. Doesn't matter what they have self-rated themselves.

If your left hand opponent opened and your partner overcalled 1 NT with 11 hcps, your partner has no idea how to play bridge. OTOH, if your RHO opened and your partner overcalled 1 NT after two passes, he can do that with 11 hcps, and you were wrong to raise. You should pass or perhaps bid a 5-card suit. His correct call with 11 hcps is to bid the 1 NT provided he has a solid stop in the adverse suit and a balanced hand. If he has a better hand such as 15-18 hcps, he would double. Hence, his overcall promises less than 15 hcps.

If your partner deals and passes the opening and it goes around the table so your LHO opens, and then your partner overcalls 1 NT, that is Unusual NT asking for a minor.