Why the Giants do it:
Joe Mauer is an amazing hitter with more than enough bat to to be an outstanding 1B. His long-term health concerns go down significantly because of the move to primary 1B (and the offsetting money). Of course, in the meantime he still carries much more value than an average 1B because of his ability to back up Posey at Catcher 60 times per year. Denard Span is a very good CF on a very good contract through 2015.
Brandon and Hector's contributions are both replaced by Joe Mauer.
Why the Twins do it:
Mauer’s contract and potential position shift loom large for a team coming off 96 and 99 loss seasons. They have a cheaper version of Denard Span in Ben Revere.
Brandon Belt and Hector Sanchez fill long-term holes at C and 1B. Positions where the Twins currently have no young players or prospects to speak of. They can move Trevor Plouffe to 2B and give Gillaspie a crack at 3B.
Twins also get two solid pitching prospects for a system in absolutely dire need. Blackburn in particular would seem like a very valued prospect to the strike heavy Twins org.
Guaranteed contracts and minimum salaries (from Cot’s Contracts)
Matt Cain, SP: $20M
Madison Bumgarner, SP: $0.75M
Barry Zito, SP: $20M
Tim Lincecum, SP: $22M
Jeremy Affeldt, RP: $6M
Pablo Sandoval, 3B: $5.7m
Ryan Vogelsong, SP: $5.3M
Javier Lopez, RP:
Brandon Crawford SS: $0.5M
George Kontos RP: $0.5M
Joe Mauer C/1B: $17M
Denard Span OF: 4.75M
Arb eligibles with estimates (from MLBtraderumors).
Hunter Pence, OF: $13.8MM (fourth time eligible)
Santiago Casilla, RP:
$5.4MM (Traded or non-tendered)
Brian Wilson, RP:
Clay Hensley, RP:
Sergio Romo, RP: $3.6MM (second time eligible)
Jose Mijares, RP: $1.6MM (second time eligible)
Buster Posey, C: $5.9MM (first time eligible)
Gregor Blanco, OF: $1.3MM (first time eligible)
Joaquin Arias, UT: $800K (first time eligible)
Estimated Free Agents:
Marco Scutaro 2B: $6M ($2y/$15M,$6.5M, $7.5M, $1M buyout or $6.5M option)
Where the Giants are left:
Estimated payroll of 135.5M with a number of holes to fill cheaply in the bullpen and on the bench. I think Brian Wilson coming off a 2nd TJ is really looking more at a low make-good $2M, so maybe he plus some combo of Hembree, Machi, Bochy, Runzler fill up the rest.
The linuep looks real purrty though! Long-term the Giants have a solid 1-2 offensive combo in Posey-Mauer they can build around, they protect Posey's legs with a luxurious backup option that only makes sense for them, and they do not greatly hamper the potential SP reinforcements that are going to be needed soon.
Blanco/RH Platoon LF