“Let’s be honest we could have been three up at the break, but if you don’t put the ball in the net you don’t win,” said the Millers boss, whose side lost the Sky Bet Championship encounter 1-0.
Evans caught his opposite number Mark Warburton on the hop with a team selection that relied more on finesse than physicality - and it worked until the interval.
But Stuart Dallas’ text book volley just before the hour was enough to clinch maximum points for the Bees who dominated possession in a one-sided second half.
Matt Derbyshire’s mobility caused the hosts all sorts of problems and Richard Smallwood had his head in his hands after a weak shot straight at Brentford keeper David Button, with the game less than 20 minutes old.
And with minutes remaining Button came to the Bees’ rescue with a brilliant fingertip save to deny Paul Green’ glancing header from a Scott Wooton cross.
Evans said: “Even if that had gone in and we’d got a point we’d have been disappointed because we dominated the game for long spells and should have left with a comfortable win.
“We know that a striker is a priority and we are scouring the country, but it’s difficult because clubs in this division have millions to spend and we have three bob.”
He added: “We should really have been out of sight by the break, but once again we’ve dominated and not got what we deserved. In recent weeks we’ve done the same and drawn, but today they have nicked it with a decent goal.”