The Lions erased a 22-point deficit during the third quarter to level the scores at the final change but could not go on with the job.
Voss said his team was still unable to read the tempo of a game and had plenty of work to do in the off-season.
He said Ash McGrath’s dash from the back half late in the match was something his team-mates should look at.
"We need a few guys that are able to do that and just take the bit between the teeth and off you go," he said.
"Sometimes the game just opens up by just someone making a decision to do something. We’ve got to get that balance right.
"I think that’s the killer instinct. One of the things as a group we have to get better at is when we’re in a position to be able to nail a side, (and) we’re probably not at that point."
Voss said there was no doubt the Lions’ competitive effort had returned, but the skills and decision making under pressure still needed work.
They missed a number of very makeable shots throughout the four quarters, with Daniel Rich, Michael Rischitelli and Jared Brennan among the culprits.
The Lions led by 21 points during the second quarter but could not capitalise.
Voss paid tribute to the Crows, who played almost three quarters with just 20 players after Chris Knights (hamstring) and Bernie Vince (knee) went off injured.
"There’s a lot of good things, but when you have a fair ascendancy on the game you’ve got to be able to put your foot down and we couldn’t," he said.
"Their end to end ball movement was quite neat, that overlapping run, they got that midfield space and created that overlap run.
"In general there’s been some big improvements over the last two to three weeks in our play and our style of play, we’ve tidied up a lot of areas but the one thing that keeps coming back is that we have to do a lot of work on our efficiency.
"We were a little bit fumbly at times if I had to be critical and just our finishing work wasn’t that flash. In terms of being able to retain the ball we were a lot better but we just couldn’t score in the end."
