The Black Cats face a must-win game this weekend against Derby County and Keane told his club's website: "It was a difficult weekend for me. I am disappointed because performances over the last few weeks have not been too bad.
"In defence of the players, I picked the wrong team. Even at 4-1 and 5-1 down, we were attacking and we left ourselves wide open, and I have to take full responsibility. That's what being a manager is about."
Keane pitched skipper Dean Whitehead straight into battle after a three-month lay-off with a knee injury, while Dwight Yorke started his first game in seven weeks following a calf problem.
In addition, Dickson Etuhu was included after playing twice for Nigeria during the international break.
Keane said: "I probably called it wrong. I played Dwight in the middle of the park with Dickson.
"Dickson was on the back of two tough international matches and Dwight had been out for a month or more, so there's no doubt that I got the team selection wrong.
"We changed it at half-time but even then, we still encouraged the players to get forward.
"That's the way I like to play, but you cannot do it all the time.
"It's a learning curve for me like it is for everyone at the club, but you cannot keep losing football matches and so far this season, we have lost too many."