Saturday was quite a day for two prospects who made major league debuts.

Phillies outfield prospect John Mayberry Jr. drilled a three-run homer off Andy Pettitte in a 5-4 loss to the Yankees. The right-handed-hitting Mayberry was recalled Friday with the Phillies needing a DH and facing left-handers at Yankee Stadium.

Also Saturday, Twins pitching prospect Anthony Swarzak quieted a red-hot Milwaukee lineup for seven scoreless innings, allowing just five hits and two walks. Replacing injured starter Glen Perkins, Swarzak earned the “W” in a 6-2 victory over the Brewers.

Two other pitching prospects, Sean West of the Marlins and Cincinnati’s Homer Bailey, made their first major league starts of the season Saturday. West fared reasonably well against the defending AL champion Rays while Bailey was roughed by Cleveland.

Although Bailey was forced to use the return-trip portion of his flight from Louisville after the game, prospects will continue to get major league opportunities to fill in for injured or struggling players. The economic downturn and subsequent frugalness of MLB owners last winter forced dozens of major league veterans into retirement. And unproven players have been getting chances to assume big league jobs all spring.

As the seventh week of the season comes to a close, 114 rookies have pitched at least one-third of an inning in the majors. That number was 198 for the entire 2008 season and 205 the year before. If you take pitchers out of the equation, the number of 2009 rookies with at least one plate appearance is 72, compared to 190 a year ago and 157 in 2007. At its current pace, the 2009 total will easily surpass those of the last two years.

More will struggle than succeed, but the opportunities are there. It’s a good time to be a prospect in the high minors.