Gareth Southgate admitted his side were embarrassed by their 5-0 humbling at home to table-topping West Brom.
Boro kicked off the day in second place and just a point behind Albion but looked leagues apart by the end.
"We've had an embarrassing defeat," confessed the shell-shocked Boro boss. "I've learnt a lot about some people and it is better to know that now than later."
Albion took a controversial early lead as Chris Brunt drilled home a free-kick with Boro claiming they should have won the decision instead.
But there was no way back for Boro as Brunt chipped in a second on the half-hour and Youssouf Mulumbu headed a third before the break. In the second half Roman Bednar and Jerome Thomas sealed it strikes in the last five minutes.
Southgate added: "We didn't have the energy to get back into the game after their opening goal and we made some poor decisions along the way. As the game wore on you could see the confidence drain away. We got exactly what we deserved.
"I don't want to make excuses but goals change games and for the first one we should have had a free-kick but instead they get one and it is deflected in.
"And for the second our keeper has done well to come out and clear but it fell to one of their men and you can't legislate for that.
"Credit to West Brom because they are a good side and they deserved to win the game. They have hit us with a sledgehammer. It has been a wake-up call. We have to make sure we use it to our advantage. We have to make sure it hurts and we have to make sure we respond properly next week against Coventry."
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