Price is still being paid his signing bonus ($5.6M) on August 31st. This is the third of six increments, and assuming it's a clean six-way split -- aren't all six-way splits clean? - that's about 933K.
Price's salary in the minors this season is $0.15M, in the majors that number raises to $0.75M. If the salary is paid on a monthly allocation - A.K.A he's paid that month based on the percentage of time spent in the minors and majors - then we're not exactly talking about a large sum saved there.
Regarding arbitration and free agency. Pitchers do not age on a curve like hitters. This means that having Price at ages 28-31 is less important than having Longoria at those ages. Ideal world: both are Rays until they're no longer useful. Real world: that might not be plausible. As it is, the Rays will have Price through the end of the 2014 season, maybe there's a chance they can push that to the end of the 2015 season. Price is 23-years-old right now, in 2016 he'll be 29. C.C. Sabathia is 28, for comparison's sake.
There's simply no reason to believe this was 100% or even 60% money driven instead of purely performance and developmentally driven. Anyone who looked up the pitch data knows Price failed to use his change in his cameo last season. Even in his lone start, Price failed to use his change-up, relying primarily on his fastball and slider.
The biggest issue here is trying to estimate how "ready" a pitcher is and comparing this situation to Longoria. There was little for Longoria to work on when he was sent down. Strikeouts and a lack of ‘failure' were the two biggest concerns. With Price, it's less obvious to see these worries, or perhaps to place relevance upon them.
I hate to be the "pro-establishment" guy, but if a staff that includes Andrew Friedman, Gerry Hunsicker, James Click, Joe Maddon, Jim Hickey, and a handful of other really, really qualified coaches and execs say that Price's change needs work along with his fastball command and efficiency, well I'm prone to believe it. At least if there's no suitable evidence conflicting the opinion. Unless there's a Pitchfx rock left unturned, that doesn't seem to exist here.