There were two Pitchers in baseball who were named Dutch Leonard.  The first was Hubert “Dutch” Leonard, who was a lefthander who had a 139-113 record with two World Series Championships with the Boston Red Sox.  The second was Emil John “Dutch” Leonard, a righthander who may not have had a World Series Ring, but had a much longer tenure and was one of the better knuckleballers in baseball history.

Dutch Leonard was a huge cog in the machine that made the Red Sox a powerhouse team in the 1910s, and while he has not received the due that he deserved, there is a good chance that they don't win the 1915 and 1916 World Series.  

A feared knuckleball pitcher (Jackie Robinson said as much), Dutch Leonard went to three All-Star Games as a Washington Senator.  For a knuckballer, Leonard had very good control, twice leading the AL in BB/9 and once and WHIP.  As a testament o his lack of walks delivered, Leonard once led the league in SO/BB, which was especially incredible considering that he was not regarded as a Pitcher who struck out many batters.

With the Senators, Leonard had a record of 118-101 with a 3.27 ERA.