Adrian Beltre turned down offers from the A's and Angels before signing with the Rangers. It turns out that one of those offers was larger than initially thought. According to Mychael Urban of CSNBayArea.com, the A's offered the third baseman a six-year, $76MM deal, not a $64MM deal as we'd heard before. Peter Gammons first reported that the A's had offered $76MM (Twitter link). The Rangers outbid both of their AL West rivals, as the Angels reportedly offered a $70MM deal.
The 2016 option in Beltre's contract is complex, as Ken Rosenthal of FOX Sports explains. Beltre needs 600 plate apperances with the Rangers in 2015 or 1,200 plate appearances in 2014-15 for the $16MM option to vest in 2016. If the option vests and Beltre's on the disabled list at the end of the 2015 season and a mutually agreed upon doctor determines that he's unable to play at a normal level by the spring of 2016, the team can defer $12MM of the third baseman's 2016 salary at 1% interest (Twitter links).