Neil Danns then fired Palace into the lead just on the hour mark, before an injury time strike from Victor Moses sealed the three points for Palace to end Town's unbeaten run.
Speaking to the Official Club Website, Keane said after the game: "It's never easy when you are a man down but I was very disappointed with the way we reacted after Steady went off.
"We didn't keep the ball well and we gave away two bad goals. The third one I'm not worried about because we were throwing men forward.
"Jon's tackle looked a typical striker's challenge, clumsy but I don't want to talk too much about that being the key. We had to react to that and we didn't and that's very disappointing. There are lots of ways to lose a game and I didn't like the way we lost that one.
"It shows you that we miss Grant Leadbitter and Jon Walters and I was hoping I wouldn't have to say that and I think our best players were the younger ones, Jack Colback, Jaime Peters and Connor Wickham, when he came on.
"Jack has the chance to go on and be a top player because he's got the right character. There are a lot of good players out there but the ones with the right character go on and achieve something."