Santi Cazorla would have been more frustrated than most, of course, slipping up late on to miss the penalty that could have given Arsenal a point.
But the expression on Sanchez's face above after the Chilean missed a chance says it all. West Brom just about had the Gunners' number and what does the result say for Arsenal's title challenge?
They remain only two points off the top of the Premier League table and didn't quite do a Manchester City (who lost 4-1 to Liverpool at home). But do the north London side really have the nerve to go all the way under Arsene Wenger?
It looks like a top-four finish for them once again, realistically. Slip-ups like the West Brom clash are just too frequent for Arsenal but one thing going for Wenger's men is the fact everyone else seems to be struggling in the same department.
Tottenham Hotspur are going strong, while Manchester United keep grinding out results. But they, too, have suffered their slip-ups, while Leicester City, Manchester City, Liverpool and more have also struggled. That's without even mentioning Chelsea.
Are Arsenal really ready to capitalise?