Lorbeck might have made more long term money had he signed with the Spurs, fought for a player option in year three, and made up the difference with a good free agency contract.
IOW, just like a Boras baseball draft clients have left bonus money on the table for a major league contract. Being on the the 40-man roster starts the clock earlier. The shorter contract is more valuable to the player under the CBA. It's a risk, but for an older European, that was a rational shot for bigger money. Instead, Lorbek has a safer contract with more guaranteed money.