Walks per nine innings tells us how many walks a given pitcher allows per nine innings pitched -- using the formula walks divided by innings times nine.
Obviously, a pitcher's goal is to keep opposing batters off the bases -- and a walk does just the opposite of that. If he allows a ball in play, he at least puts the outcome in the hands of his defense -- and luck. But a walk gives the team behind him no chance to help.
In A Call
"walks per nine," "walk rate per nine," "walks per game"