"This is a massive blow for us, without a doubt. We were absolutely fantastic in the first half and it looked like game over," Redknapp said after the 3-2 defeat on Saturday.
"Once Cole and Solano came on it was a different game. We stood off them and let them play.
"We needed the three points today, that's for sure, and it's going to be very hard to get out of trouble.
"West Brom didn't play today but they have had a great afternoon the way results have gone for them.
"Our problem is that we have no talkers at the back and we got deeper and deeper in defence. There's a lack of pace at the back which invites pressure and the nerves got to us.
"There's not much to bring in in the way or replacements but when we were two goals up and playing great that was the last thing to worry about.
"The big turning point came for them when Vassell went off and when we lost Jakobsson from our defence. That transformed the match."