Ruben Amaro Jr. didn't have to trade Cliff Lee. For that matter, the Phillies' general manager didn't have to pursue Roy Halladay, the righthanded ace he acquired from the Toronto Blue Jays this week.

The easy and safe thing would have been to stand pat. If the Phillies had gone into 2010 with Lee and Cole Hamels at the top of their rotation, no one could possibly have criticized Amaro for not adding Halladay.

So start with that acknowledgment, that Amaro took a pass on safe and easy and made a daring stroke to improve the best team in the National League - not just for 2010, but for the next four or five years.

"I didn't really want to move [Lee]," Amaro said. "But I really felt that this is the best way to go about getting to the goal."

After three wild days, Amaro finally explained his thinking on the great Cy Young Swap of '09. What emerged was a coherent picture of both the logic behind the trades and the enormous risk Amaro was willing to take.

"Is it going to be the right decision?" Amaro said. "That remains to be seen. I do not know that. Is it risky? Yes, because we're moving a lot of talent out of our system. But I don't mind taking a risk on a guy that I feel is one of the best pitchers in baseball."

It all starts there. Lee is a terrific pitcher, a Cy Young Award winner who delivered at the highest level in the playoffs and World Series. But Halladay has been a more dominant pitcher, with more overpowering and varied stuff, for significantly longer - even though he's just a year older than Lee.

The decision to add Halladay was easy. The trouble was that the deal with Toronto further gutted a farm system that had already been raided to acquire Lee in July, not to mention the Joe Blanton deal in 2008.

"We could not leave the cupboard bare," Amaro said.

So Amaro sought an accompanying deal that would bring in some legitimate prospects to offset the talent drain. When he looked at his team, there weren't many players he could dangle as bait. Blanton wasn't going to do it. J.A. Happ wasn't going to do it. Amaro certainly didn't want to mess with the lineup that has carried this team.

Cole Hamels surely would have brought the kind of talent Amaro was looking for, but that's only because the rest of baseball believes what the Phillies do - that the 25-year-old lefthander is going to be an elite pitcher for years to come.

Then there was Lee, who had one year left on his contract and who wasn't interested in the kind of medium-length extension Halladay was willing to sign. The Seattle Mariners were willing to part with genuine prospects. It didn't hurt that Amaro's assistant, Benny Looper, worked in Seattle until last year and is intimately familiar with the Mariners' system.

The logic is unassailable. The Phillies are built on homegrown talent: Ryan Howard, Jimmy Rollins, Chase Utley, Hamels, Happ, Ryan Madson, Carlos Ruiz. They have been able to do difference-making trades - Lee, Blanton, now Halladay - because they had desirable talent in their minor-league system. To keep that going, they simply needed to restock the minors.

"We were tapped," club president Dave Montgomery said. "We weren't going to focus on 2010 and ignore the future. Our goal, and our mandate from our fans, is to be as good as we can be for as long as we can be."

The counterargument is that fans want to go all-out next year - and everyone agrees the Phillies would be better with Lee and Halladay for the short term - and are willing to trade a few down years in exchange for one championship.

Fans making that argument are proving themselves wrong. The Phillies just won the World Series 14 months ago doing things their way. They retooled and went back to the World Series this year. Any fans griping because they think the team is too cheap to keep Lee are proof positive that Montgomery and Amaro (and the Eagles, for that matter) are right: Fan enthusiasm will fade the moment the team starts to fade.

In Halladay, the Phillies have an ace for the next four or five years. With Hamels, Utley and a few others, they have a bridge beyond 2011 - when contracts for Howard and Rollins expire and things get really complicated. These Mariners prospects, along with Domonic Brown and a few others, give the Phillies some options.

Amaro's moves here are both smart and bold - smart because they make sense and bold because there's absolutely no way to know if he's right. That's up to Halladay, Lee, and Hamels to decide.

Contact columnist Phil Sheridan at 215-854-2844
Read his recent work at http://go.philly.com/philsheridan.