Lancashire strengthened their grip at the top of Division Two with a comprehensive innings victory over Glamorgan in Colwyn Bay.
The Welsh county went into day three 288 runs behind, however were bowled out for 138 in their second innings.
"The belief was there we could get something out of the game, but they bowled really well and we weren't good enough the whole game,” said Cooke.
“They outplayed us with bat and ball and in the field. We couldn't match their intensity.
"We've got to brush ourselves down because there's still a lot to play for, going into September with promotion to fight for, which hasn't been the case in the nine years I've been at the club.
"Potentially the T20 form has affected it, but we had a bad game against Middlesex before that.
"Hopefully we can get a bit of momentum in these next few T20s then we've got a week off when we can prepare well for Worcester."