The Australian star scored yet another header when the Toffees defeated Manchester City 2-1 on Monday night and Keown is perplexed as to why opposition defenders do not pay the former Millwall man the respect he deserves.
'It seems ridiculous saying it when he's 31 and been in the Premier League for six years but teams almost need to pay him a bit more respect now and try to cancel him out - that's how dangerous he is,' Moyes wrote in his column for the Daily Mail.
'Now he's a thorn in the opposition's side who will run around all day attempting to get on to the end of things.
'He just pops up all over the pitch.
'At the set-piece you cannot let him get his head on the end of things because he's too dangerous. But even from general play you cannot fall asleep.'