Adamant was the wrong word. Lets just say, that he really would like to stay under the tax unless he is blown away.
Lets put it this way. Lets say....
Beltre signs for 9 mil a yr for 3 yrs. It put them over the luxury tax by lets say 5 mil for 2010. That 5 mil is taxes at 40% for 2010, so overally, in yr 1, Beltre would cost $11 million. Now, if they didnt sign Beltre, the lux tax would be 22.5% in 2011 and 30% in 2012. Instead, with Beltre, they'd be at 40% for both those seasons. So, lets say the sox are $10 million over the cap in both 2011 and 2012. Beltre would cost them $10.75 million and $10 million for those seasons. So, instead of 3 yrs 27 million, it becomes 3 yrs $32 million. Is Beltre worth $5 million more than his salary in extra sunk cost? And, that figure assumes the sox are only $10 mil over the cap in 2011, which might be underestimating.