Gardner is basically a poor man's Michael Bourn but you're right, I'd never spend $12M per for 4 years on a center fielder who is at the age where similar players usually erode quickly. All you have to do is look at the players who compare similarly to him at age 29:
1. Max Flack - played forever and a day ago, I'm not even going to compare him.
2. Brett Butler - the only player on this list who is the exception, had his best years from 29-33 and had a long career.
3. Dave Collins - center field days were done by age 29. He was an offensive liability as a corner outfielder.
4. Roger Cedeno - career done at 30.
5. Brian Hunter - career done at 32, effectively he was done 2 years earlier.
If I was a Met fan I would be grateful my team didnt spend almost 50 million dollars on a player with the same skill set as Brett Gardner. Good defense good speed almost no power and an absurd amount of strikeouts.
The comparison between Gardner and Bourne is pretty true. Given that Gardner is a little younger and under control for two more years...I wonder how much trade value he might have had this offseason. This might have been a pretty interesting offseason if the front office had a little more creativity.
You're comparing an all star to a guy who barely played in 2012, you do realize that right?
As a general rule a player's home team knows him better than anyone. That is not always true, but it usually is. Bourne's home team traded away some very valuable parts and added salary rather than keep him in center field. Gardner's home team is willing to count on him to play 150 games this season and is so sure of his health...it did not spend the extra money to sign an extra outfielder. That tells you something about the what the organizations think of the players.
If you look at what they have done in their careers, Gardner's numbers are pretty close to Bourne's. No one in baseball tracks a fly ball much better than Brett. And he costs $9 M less. Yes...he has trade value.