Which batters make the pitcher work the most? One way to measure this is by pitches per plate appearance. But there is a big difference between working a 9-pitch walk and working a 9-pitch groundout. The best hitters make the pitchers throw a lot of pitches, and don't use up one of their team's outs in the process.
Here are this year's leaders among players with 100 or more plate appearances, through June 9th: