One thing that's become abundantly clear over the last two offseasons is that teams are all about mitigating risk. Long-term contracts have disappeared for players considered to be anything less than elite, and older players have a hard time finding guaranteed big league jobs in any capacity. As shorter contracts have become the norm, we've seen more option years included in deals.
Players are generally reluctant to agree to club options because, obviously, they'd like to retain some control of their future. On the other side of the coin, teams don't like giving out player options because of the risk and cost uncertainty. However, we've seen more mutual options given out this offseason than at any point in the recent past.
With a mutual option, both sides need to agree to continue the relationship for the option to take effect. If either side declines, then the two sides part ways, so no one has a chance to get burned. It's not uncommon to see an arrangement where the player forfeits the buyout if they're the one to decline the option. Looking at our 2011 free agent list, I see no fewer than a dozen players who agreed to mutual options this offseason, including Trevor Hoffman, Vladimir Guerrero, Jon Garland, Russell Branyan, and Nick Johnson.
For all intents and purposes, mutual options are pointless as far as being an actual option. The one benefit they do provide is the guarantee of more money in the form of a buyout. Even better, these buyouts generally do not count against this year's payroll. Think of it as a way of borrowing from the future to help in the present. Whether or not this trend continues remains to be seen, though it certainly seems to have its advantages.