The starting rotation has been the Phillies' greatest strength for quite some time, and it remains so this season. Ruben Amaro Jr. has spent more than $400 million on that position since becoming the team's general manager shortly after the 2008 World Series celebration.

Most of his biggest and some of his best transactions have been starting pitchers. Like most general managers, Amaro believes the door to big-league success can be opened only with a quality rotation, and that is a good place to start.

One problem: Even though the Phillies still have a solid rotation, it is not extraordinary, it is not deep, and it is not nearly enough to compensate for the team's shortcomings on defense and in the bullpen.

Another problem: Opposing rotations in the National League, including those in the National League East, have all caught up to and passed the Phillies as the game reverts to a time when offense was scarce.

Three seasons ago, when you held National League starting rotations under the light, it was clear that the Phillies were a cut above the rest. With their Four Aces and surprising rookie Vance Worley, the Phillies held opponents to three runs or fewer 91 times on their way to a franchise-record 102 wins. A year later, the Phillies held opponents to three runs or fewer only 71 times. The number slipped to 68 last year.

Regardless of the opponent, when the Phillies lined up Roy Halladay, Cliff Lee, and Cole Hamels in 2011, they were going to win at least two of those games, and quite often they won all three.

It's not like that anymore, and this weekend's series against the Washington Nationals is a perfect example. The Phillies shuffled their rotation after Wednesday's postponement to get their version of the Big Three lined up against the Nationals.

Lee will pitch Friday against Stephen Strasburg, A.J. Burnett on Saturday against Tanner Roark, and Hamels on Sunday against Gio Gonzalez. You can make a case that each of those pitching matchups favors the Nationals.

You expect the Phillies to be in almost every game pitched by Lee, but Strasburg has just as much cachet and better stuff than the Phillies ace. Just compare them since 2012. Lee went 23-19 with a 3.03 ERA; Strasburg was 25-17 with a 3.18 ERA.

The Saturday game will match Burnett against Roark. Burnett had a great April after two strong seasons with Pittsburgh, but Roark is 9-1 with a 1.98 ERA in his 19 career games. Hamels, meanwhile, will be opposed by Gio Gonzalez, whose 35-17 record and 3.13 ERA since 2012 matches up quite nicely with the 25-22 record and 3.41 ERA the Phillies lefthander has posted during the same period.

Jordan Zimmermann (41-29 with a 3.13 ERA) is also in a Washington rotation that has surpassed the Phillies'.

It's not just the Nationals who have a better rotation. Even without Mike Minor, who returns Friday from a shoulder injury, the Braves rotation posted a major-league low 2.32 ERA in April. The New York Mets won't have their ace, Matt Harvey, this season, but Zach Wheeler, Jenrry Mejia, Jonathon Niese, and Dillon Gee are all young arms who appear to be emerging as quality starters.

In 21-year-old Jose Fernandez, the Miami Marlins might have the best young pitcher in baseball, and 24-year-old Nathan Eovaldi has the look of an outstanding No. 2 starter.

Much of the blame for the fall of the Phillies in recent seasons has been placed on the bullpen and the demise of the aging core. Great starting pitching can cover up a lot of things, which is exactly what happened in 2011, when the offense and the bullpen started slipping.

This Phillies rotation is not close to great. In fact, the Phillies starters finished April with a 5-9 record and a 4.06 ERA. No team in the National League East got fewer wins from its starters, and no team in the division had a higher ERA.

In theory, that should improve with Hamels back from the biceps tendinitis that delayed the start of his season. Still, the strength of the Phillies isn't nearly what it used to be, and it's not going to be nearly enough to compensate for this team's other weaknesses.