I guess TV spots showing Frank McCourt and Eric Gagne rollerblading around Venice Beach were out of the question. From the LA Times’ Bill Shaikin :

Ad wars: The blue empire strikes back.

One month after the Angels added Los Angeles to their name and painted the Southland in red billboards, the Dodgers are unveiling a marketing campaign with the slogan, “This is L.A. baseball.”
 
The ads, on the backs of buses starting this weekend and on billboards starting next month, feature images of former Dodger stars morphing into pictures of current players. In one ad that highlights Cy Young Award winners, Sandy Koufax blends into Fernando Valenzuela, who blends into Eric Gagne.

In another that displays three generations of shortstops, Pee Wee Reese gives way to Maury Wills, who gives way to Cesar Izturis.

“It really connects the Dodger heritage to the present day,” said Lon Rosen, the Dodgers’ executive vice president and chief marketing officer. “We want the fans to have a connection to our history. And we think a great way to sell our team is by using our players.”

The Angels put up 480 billboards ” with no players, just the message “City of Angels” ” including several in the shadow of Dodger Stadium.

Rosen said the Dodger campaign would include “hundreds” of billboards and bus backs across Los Angeles and San Bernardino counties, but not in Orange or Riverside counties. If fans in those areas do not catch the Dodger ads while commuting, Rosen said, the team will reach them with its upcoming television campaign.

Rosen said the Dodgers had planned their marketing strategy before the Angels’ billboard blitz.

“It really isn’t a response,” he said. “We came up with this in October. This is a celebration of our history and tradition.”