The reasoning for the Mets making this trade is a no brainer. With the Bernie Madoff mess and Jose Reyes' impending free agency hanging over Citi Field, the Mets need to find ways to save money. Trading K-Rod and his potential $17.5 million deal for next season is a great start. If you're not contending for a playoff spot, there is just no need to have a closer making over $10 million a year, let alone the money K-Rod was making. In the short term, the Mets can turn to Bobby Parnell and Jason Isringhausen to handle the closing duties.
The trade also means Carlos Beltran should keep his bags packed and be ready to leave. According to ESPN's Buster Olney, there are seven teams actively talking to the Mets about trading for Beltran. Beltran is in the last year of his contract and almost certainly won't be back with the Mets next season so the right thing to do is ship him off for prospects and build for the future.
As for the Brewers, the trade is a risky but bold move. The trade clearly states that the Brewers are going for it all this season. And why not? They've got 2 of the best young hitters in the game (Braun and Fielder), two of the best young starters in the game (Grienke and Gallardo) and now two of the better closers of the last two seasons. K-Rod's addition has basically turned Brewers games into 7 inning affairs: don't get to their pitchers in the first 7 innings, be prepared to be shut down by K-Rod and Axford.
The big risk for the Brewers is that $17.5 million vesting option K-Rod has for next season. If K-Rod finishes 55 games this season, the option automatically kicks in for next season. K-Rod is currently at 34 games finished. The Brewers will most certainly use Rodriguez as a set up man to Axford. However, if Axford was to get hurt or go into a slump, the Brewers would be forced to use Rodriguez as their closer, putting the option at risk of being activated.
Another question this trade brings up (albeit a minor question) is about Prince Fielder. Could the Brewers also be making this trade with the mind set that if they let both Prince and K-Rod walk after the season, they could be in line to pick up 4 draft picks and help restock their deflated farm system? Just something to ponder in what should be a rest of July full of trades and rumors.