West Coast coach Adam Simpson was disappointed his team could not break through for its first win since round two, with the club's record losing streak extending to 15 games in a 38-point loss against Richmond.

The Eagles were in an arm-wrestle of a contest for most of the match but the Tigers' burst either side of half-time kept the home side at arm's distance at Optus Stadium on Sunday. 

The coach was pleased for senior midfielder Andrew Gaff, who was moved to the substitute role after a poor run of form but responded with one of his best games of the season after replacing injured midfielder Reuben Ginbey in the first quarter.

The dual All Australian played with intent and laid some early tackles before winning 12 of his 24 disposals in the second quarter, with Simpson now likely to recall the 31-year-old to the 22 against Carlton next Saturday. 

"I get the criticism of Gaff, and Gaff's been struggling a little bit, but I thought he was excellent when he came on," the coach said.

"He's been working his backside off all year, all pre-season, and it just hasn't clicked for him.

"I suspect a bit of it has got to do with how we're going. He complements some other things in our game, and today he got on the inside a little bit. We still value what he does for us.

"It was as much about Gaffy getting the ball but also his confidence that he's still got it, because as a player sometimes you question it and until you get some evidence it's hard to shake it. Hopefully there's some evidence there today."

Simpson also paid tribute to premiership forward Jack Darling, who kicked his 500th career goal, joining champion Josh Kennedy (712 goals) and dual premiership full forward Peter Sumich (514) as just the third West Coast player in history to reach the milestone.

"He probably goes down as one of our greats. You kick 500 goals, and he's still got some footy left in him, a premiership player, and rarely misses," the coach said.

"I know he gets maligned sometimes, and it's tough to be a forward in our side at the moment, so for him to hit 500, I'm really proud of him and for him to get up today was big."