My FanGraphs colleague Marc Hulet is doing a series on Baseball Analysts where he looks at teams from 10 years ago (1999), here's what he said about the '99 (Devil) Rays:
The Tampa Bay Rays | 69-93 (Fifth)
The Rays club has arguably come further than any other organization in 10 years. The 1999 season was just the second season in the brief history of the club. The organization received 34 home runs out of Jose Canseco and 32 bombs from Fred McGriff. Hall of Fame third baseman Wade Boggs played his final MLB season and finished the year with a .301 batting average and a .328 career average. Closer Roberto Hernandez led the club with a salary of $6.1 million (Why does an expansion team need a top-tiered closer?). He did earn his money, though, by saving 43 games. Wilson Alvarez led the club in wins with nine. Bobby Witt threw a team-leading 180.1 innings and managed a record of 7-15. Thirty-five-year-old rookie Jim Morris made headlines by appearing in his first Major League game.
Underline is mine.
Think about it, you're the GM of a new franchise, you know three things for sure:
1. You're not going to win in year one, probably not in year two, and maybe in year three. That's assuming you're a really good GM.
2. Closers are overpriced and often overvalued.
3. Closers are only useful to good teams and teams who can build a closer then trade him for prospects.
The Rays sorta dealt Hernandez for prospects -- well, Ben Grieve -- but that came three years after they signed him and after paying him ~17 million.* I'm going to guess the Rays knew #3, and kinda figured #2 out -- they would only slightly overpay Danys Baez, he would earn ~5.6 mil for ~3.7 mil worth of performance. Which means they didn't know or -- more likely -- didn't believe they would be poor in the immediate and near future.
So, that's why an expansion team needs a top of the line closer; when they don't realize they're an expansion team.
They also gave up Cory Lidle, who was cheap and league average. Of course, if Grieve doesn't lose all traces of power after donning a Rays uni, the deal probably doesn't look too bad, but that's beyond the original point: the Rays overpaid for something they didn't need just to fit in with the rest of baseball.