Cubs showing they trust Rizzo

MESA, Ariz. -- As Ryan Howard, Adam Dunn and numerous other big leaguers can attest, nothing presents a bigger challenge for a left-handed hitter than trying to hang in the box against lefty pitching.

Some guys, like Baltimore's Chris Davis, seem to improve with repetition and time. Others, like Howard, find it never really gets better. The Big Piece is making $25 million this year, and his substandard production against lefties has fueled speculation about a possible platoon situation at first base in Philadelphia.

In Anthony Rizzo's first two seasons in Chicago, the Cubs haven't been shy about throwing him out there against the Francisco Lirianos, Madison Bumgarners and Wade Mileys of the world. The numbers were rugged in 2012, when Rizzo hit .208 with a .599 OPS against lefties. His problems continued last season, with a .189 batting average and a .625 OPS.

So it was a positive -- albeit small -- early sign when Rizzo doubled and singled off lefty Tommy Milone in a 6-4 victory over Oakland Tuesday. But he still has a lot of work to do in spring training and beyond with new hitting coach Bill Mueller, who replaced James Rowson in November.

Rizzo made 158 starts at first base last year, and barring a change of plans, the Cubs have no plans to sit him against lefties to protect his numbers or his self-esteem this season. His education on the fly will continue in 2014.

"There's a fine balance in allowing an individual to face the pieces that give him the most trouble," said Cubs manager Rick Renteria. "We think Anthony's opposite-field approach in general should allow him to transition against lefties a little better. He just needs to trust it."