The Oakland A's are retooling. The Toronto Blue Jays are reloading. And it's likely neither team is done this off-season.

Last week, the Athletics traded their best position player, third baseman November 29, 2014

What he's done over the last two years has been tremendous.

And it's not only Donaldson's bat that makes him a valuable player. Over the last two seasons, he ranks fourth among all third basemen in Defensive Runs Saved.

Donaldson is also a "Super-2" player, which means he'll be arbitration-eligible for four years rather than three, meaning he can't become a free agent until after the 2018 season. He's expected to make about $4.5 million next season.

If Oakland is expecting to be better next year, there is still a lot of work to do.

They do get a useful piece in Lawrie, who is four years younger than Donaldson (he turns 25 in January), and is someone they feel still has a lot of upside. But getting a productive Lawrie will be key for this deal to work for the A's. And staying on the field has been Lawrie's big problem.

Lawrie has not played more than 125 games in a single season in his career. However, he is as good a defender as Donaldson at third, totaling 38 Defensive Runs Saved from 2011-2014, tied for second-most among all American League third basemen. And he does have some pop in his bat.

Oakland believes it is acquiring a player with a lot of upside, in addition to two Major League-ready starters and a shortstop that scouts are crazy about.

As for Toronto, the acquisition of Donaldson makes a lot of sense.

They had given up on Lawrie, frustrated with his inability to stay on the field. So they dealt him and gave up two arms and a good shortstop prospect in the deal for Donaldson. But for a team that is in clear win-now mode, it was an easy call to make. And, with the recent addition of Russell Martin, Toronto has what could be the best lineup in the American League East.

Donaldson moves to a much friendlier park for hitters by leaving the Coliseum for the Rogers Center and will join Jose Reyes, Edwin Encarnacion, Martin, and Jose Bautista to form a formidable middle of the order. Toronto gets a player worth about five-to-six wins a season. That's a useful human.

It's unfair to make a judgment on this deal before the rest of the winter plays out. Both teams are probably not done adding and subtracting to their rosters. Oakland still needs a ton of help at shortstop and second base and could still flip a pitcher like Jeff Samardzija for help there.

Toronto could still add an ace starter to the mix - perhaps Jon Lester, Max Scherzer, or James Shields - or make a trade for a pitcher like Cole Hamels. And the Jays could still use a left-handed hitter, as well, to balance out all those righties.

It's a fascinating trade for both clubs, and it shows two things.

The Jays are making a serious run this season.

And the A's are in transition.