Lake, 25, played parts of the last two seasons with the Cubs and batted .243. At Triple-A Iowa this season, Lake was hitting .289 with two doubles and eight RBI in 13 games.
To make room for Lake, the Cubs optioned struggling RHP Brian Schlitter to Iowa. Schlitter is 0-2 with a 9.53 ERA in seven appearances.
With the move, the Cubs are down to 12 pitchers.