Joe Kelly stat rankings for qualified relievers:
HR/9 - 13th
BAA - 33rd
ERA - 39th
WHIP - 63rd
WAR - 65th
IP - 102nd
K/BB - 139th
Those numbers don't look great, but if you consider that there are 30 teams with 7 relievers per team, they are not bad at all. Yes, Kelly gives up too many walks. OTOH, he doesn't give up that many hits which gives him a respectable WHIP.
To me, he is a #2/3 quality reliever on a team, which makes him a 7th or 8th inning guy.