The right-handed Tolleson went a combined 7-2 with 25 saves and a 1.17 ERA in 57 relief appearances with Single-A Great Lakes, Class A Rancho Cucamonga and Double-A Chattanooga this season.
A 2010 30th-round Draft pick, Tolleson needed Tommy John elbow surgery in March 2006. A starting pitcher at Baylor University, the Dodgers moved him to the bullpen last year where he excelled, posting an 8-3 record with a 1.01 ERA, 144 strikeouts and 23 walks in 98 innings.
The right-handed-hitting Van Slyke won the Double-A Southern League batting title with a .348 average in 130 games with Chattanooga, and was the MVP of the Southern League Midseason All-Star Game. A 2005 14th-round pick, Van Slyke is the son of former Major League Andy Van Slyke. A late bloomer in his seventh professional season, the Dodgers must protect him or risk losing him in the Rule 5 Draft in December.
Tolleson and Van Slyke will be honored in an on-field ceremony prior to Friday night's game against the Pittsburgh Pirates.