Middlesbrough boss Gareth Southgate was shell-shocked after their 3-0 defeat at West Ham.
"But they have effectively won the game in the first five minutes of the second half.
"It's a harsh lesson for us, we didn't get out of the blocks in the second half, but we'll learn from it.
"I'm not going to bring any criticism out of the dressing room. We got plenty of pats on the back after our last game, but this time, five or 10 minutes has cost us."