NEW YORK (AdAge.com) -- Baseball fans will be straddling the fence on this one.

The Chicago Cubs have entered into a sponsorship agreement with sports apparel company Under Armour that includes signage on the ivy-covered outfield walls at historic Wrigley Field. The Under Armour logo will appear on the two doors in left and right field, and the company will also have signage rights behind home plate.

Financial terms of the two-year deal were not announced.

Built in 1914
Venerable Wrigley Field is the second-oldest ballpark in the country. Built in 1914, the famed ivy-covered walls were added during a renovation in 1937, and the two outfield doors that lead to the bowels of the stadium were painted green to blend in with the ivy.

The decision is bound to cause some debate.

But baseball diehards -- particularly Wrigley Field denizens -- will almost certainly decry the advertising creep taking place. After all, it was a group of Cubs fans that for years fought the good fight to keep night baseball out of Wrigley after the Tribune Co. bought the team in 1981 and announced its intention to add lights. The lights were finally added in 1988, in large part because Major League Baseball threatened to move any potential playoff games to a site that did have lights.

Outfield ads
But baseball historians will note that stadiums regularly featured advertising on outfield walls during the heyday of the game, including the famous "Hit Sign, Win Suit" ad at Ebbets Field, former home of the Brooklyn Dodgers, in the 1940s and '50s.

"I think everything we do is very measured. We certainly do keep the fans in mind, the aesthetics in mind, and that's why you haven't seen this before or more advertising than this," said Jay Blunk, the Cubs director of marketing. "At this particular time in the organization's history, these revenues go directly to payroll."

At this particular time, the Cubs are spending money and need the influx of sponsorship cash. Chicago, which has been mired at the bottom of the National League's Central Division the last few years, spent $300 million in the off-season on free agents to bolster the team, including $136 million for outfielder Alfonso Soriano -- who, coincidentally, is an Under Armour endorser.

Moreover, of the teams in Chicago's division -- St. Louis, Houston, Milwaukee, Cincinnati and Pittsburgh -- all have moved into new stadiums within the last five years, giving those franchises additional revenue streams through naming rights, luxury suites and more.

'Norman Rockwell painting'
"We play baseball in a Norman Rockwell painting every day," Mr. Blunk said. "[Wrigley Field] is a tremendous asset to the organization but it takes millions of dollars to maintain. Our challenge is to find these new revenue streams to compete."

Mr. Blunk said it was important that the outfield signage be related to baseball and competition, rather than doing a deal with, say, an insurance company or car company. Under Armour, which also has its logo on the famed "Green Monster" left field wall at Boston's Fenway Park -- the nation's oldest ballpark -- is launching a new ad campaign this spring, done in-house, that touts its new baseball cleats.

"The timing was right for everybody," said Steve Battista, VP of Baltimore-based Under Armour. "I talked about this two years ago with [Cubs president] John McDonough, but the ball club wasn't going in that direction then. But the tide has really turned and there's a new way of thinking."