You can't expect to allocate every dollar on the payroll for "good value." Free agents, esp. the best in their class, are paid at outsized rates because of market demand. The best value comes in the form of pre-arb players, arb. eligible players, and long term contracts signed early on (not always, see: Mauer)--those are either home-grown players or players acquired very early in their careers via trade/waivers/etc. We can't expect to use all of our payroll resources exclusively on in-house talent or we won't be spending close to what we should be allocating in payroll. So payroll expenditures beyond those for in-house players, will necessarily come from the free agent class where the market and not necessarily value dictates price. (Of course you could acquire players via trade, but that cost is quite high too, both paying an established player and paying value in terms of the teams own assets). Given that we have Mauer, etc. coming off the books after this year, and Hughes etc. after next, signing Darvish now is likely to interfere less with any potential free agents in a couple years or in-house costs later. If we don't spend the payroll resources on Darvish, it will simply go unspent, and in another free agent class, we may have even less a chance to recruit such a free agent, we would face the same dilemma of paying them at a rate which is outsized compared to their supposed value, and we'd have a shortened window with which to pay a player such an outsized amount (i.e. before Buxton, Sano etc. need to get paid).