Team WHIP (walks plus hits per inning pitched) is the average number of hits and walks (including intentional and unintentional) that a team's pitching staff allows per inning.
WHIP = Walks + Hits / Innings Pitched
More about Team Walks Plus Hits Per Inning Pitched - WHIP
With the decline of offense in the last decade this figure has gone down somewhat, and due to less offense in the National League the league leader is usually a National League pitching staff. Generally speaking a team’s starting rotation will have a slightly higher WHIP than a team’s batch of relievers, as they are asked to throw more innings and thus will generally allow more baserunners. However, overreliance on a team’s bullpen can drain their effectiveness, which is an important aspect of bullpen management.