Walcott is set to sign a deal worth a mooted £88,000-a-week.
If Olivier Giroud and Lukas Podolski were playing well and Santi Cazorla was getting bags of goals, Theo Walcott would have left Arsenal in the January transfer window," Robson told talkSPORT. "Theo Walcott has come along at just the right time and will get paid double what he really deserves.
"Theo Walcott is overrated. He's got good pace and is looking like a good finisher but his general game understanding is not very good. Most of the other players at Arsenal have a better technical understanding of the game.
"Walcott is too hit and miss. He'll have a good couple of games and then play like he did against Southampton where he couldn't hold up the ball. He had to be swapped to the right wing because he was so ineffective up front."