Check this out.
The Mariners are over 10 games out of 1st place in the AL West, and well below .500. Why would they trade two fringey prospects (Ezequiel Carrera, Juan Diaz) to get back Russell Branyan in a lost season? There are two simple reasons, one being much bigger to the Mariners than the other.
Even if the team and many fans (such as many reading here, myself included) have given up on the season, many local/regional fans still might have an interest in attending Mariner games, so long as the team can make a significant effort to win, i.e. not make the cost and time invested to see a game a complete waste of their time. A team that scores 3 runs a game and is clearly/obviously punting the season isn’t going to draw most casual fans.
But believe it or not, the ticket sales side of the equation is the small part. Ticket sales, while valuable, make up a minority of the team's revenue. The biggest reason why Jack would want to buff up 2010’s team in a lost season is that the team's in-season performance from here on out does matter to the team’s relationship with FSNW and ESPN Radio, given the networks are paying the Mariners a lucrative sum for their media contracts.
A better team that competes despite the record equals more game-to-game interest which means more ratings. More interest in the team in 2010 means more viewers in 2010 which means higher average ratings during 2010 as well as over the life of the current contract, which means more ad dollars down the line.
If ratings for Mariners broadcasts tank, a) FSNW loses money in the long run as advertisers can cite lowered average ratings as justifiable leverage to lower the price on ad spots with the network and b) the Mariners may lose out on money from a new radio or TV contract down the line, as the network side will cite low ratings from this period as justification for low-balling the M’s when it comes time to negotiate a renewal. Sure, the Mariners have a 10 year, $300 million deal with FSN through 2020, but let's say the team wanted to buy out and jump to a more lucrative deal, or let's say FSN wanted to nix the deal. Don't forget the radio deal with KIRO ($5.5 million per year) only lasts through 2011. There is still plenty of leverage, as well as money, that can be gained and lost by what team they elect to field for the rest of 2010.
Even if the team's playoff chances in a vacuum make upgrading the 2010 roster seem like a waste of time, doing so could have an impact that reaches way beyond the field, and way beyond 2010.