That either pitcher is in such a consequential conversation is a testament to how well they've fared in two of the game's more pressure-packed environments.
"I'm not surprised," a clearly confident Nova recently said of his results. "I know what I can do."
And now, so do we.
You could argue that Nova (15-4, 3.94 ERA) will be as big an AL X-factor as anybody in October, because it's obvious what the Yankees' lineup is capable of unleashing upon opponents. If the bulk of Nova's regular-season results are any indication, he is seemingly fit for the game's most high-profile stage, though one can never be certain how well a 24-year-old with no postseason experience will rise to such an occasion. Nor do we know for certain if Nova has simply been more lucky than good.
What we know is that Nova has helped alter the outlook for a rotation that was criticized long before 2011's first pitch. As expected, Sabathia has been a rock, but the question was always what the Yanks could reasonably expect from the other four spots.
Phil Hughes was the projected No. 2 at one point, but shoulder and command woes left him diminished. It's only natural to assume the $16.5 million the Yanks are paying A.J. Burnett this season (and the remaining $33 million they'll owe him in 2012 and '13) has a lot to do with the patience they've shown in him, but he's certainly not somebody you'd trust at the forefront of your rotation at this point. Likewise, Bartolo Colon and Freddy Garcia, who have been major success stories considering how little fanfare there was when they signed. But consistency has hardly been their strong suit, and fatigue could be a factor with Colon, in particular.
All this serves to turn one's head toward Nova, and he's been turning heads all year. The only extended interruption to his AL Rookie of the Year Award bid came when the Yanks shipped him back to Triple-A for a spell in July, when Hughes returned from the disabled list. Upon Nova's return at the end of July, his performance compelled manager Joe Girardi to go with an unconventional six-man rotation.
Are Nova's numbers a product of talent or luck? After all, his run support average of 9.5 per nine innings leads the AL. His 5.44 strikeouts-per-nine innings is below average, and his 3.13 walks-per-nine is about average.
Where Nova separates himself from the pack (and where he could be an October commodity) is in his ability to induce ground balls. His 1.21 ground-ball-to-fly-ball ratio is among the best in the league. That has combined with ample run support to help the Yankees go 18-6 on days he starts, including 12-1 over his past 13 starts.
"It's hard to [achieve] the run he's been on," Girardi said. "It's not easy to do. Can I say I expected this? No. Were we hoping we'd get a real good year out of him? Yeah."
Under ordinary circumstances, Nova would profile as a fine fourth or possibly third starting option, regardless of his level of experience. But the uncertainty surrounding the rest of the arms at Girardi's disposal might slot Nova into that spot right behind CC. And that's the spot that is largely going to determine how far this Yankees club advances in October.
Worley isn't in contention for quite so lofty an assignment. With Roy Halladay and Lee both as untouchable as ever and Cole Hamels seemingly OK after recent shoulder concerns, they are easily the favorites to advance out of the best-of-five NL Division Series.
What's on the line is that potential Game 4 spot in the NL Championship Series. Make of this what you will, but since the best-of-seven format was adopted in the LCS in 1985, the Game 4 winner has claimed the series 35 out of 50 times, including 17 of the past 22.
Will manager Charlie Manuel go with youth or experience in that spot?
Knowing Manuel, bet on the latter. The assignment would seem to be Oswalt's to lose. But that doesn't mean Worley isn't doing his part to force the issue.
Like Nova, Worley has benefited from some good fortune. For all his success, which includes an 11-2 record and a 2.92 ERA in 21 games (including a tough-luck loss to the Brewers on Sunday), the concern with Worley has been his high line-drive rate of 23.7 percent, according to Fangraphs.com, and what had earlier in the year been an abnormally low batting average on balls in play, no doubt a product of the Phillies' excellent defense.
However, even as Worley's BABIP has risen to near the league norm in recent weeks, he has remained successful. The primary reason is that he's doing a much better job of putting opposing hitters away and not allowing free passes. In the first half, Worley had a walk rate of 9.7 percent and a strikeout rate of 17.9 percent. In the second half, he has cut his walk rate to 6.1 percent and elevated his strikeout rate to 23.7. Most rookies tend to regress as the league adjusts to them, but Worley appears to be doing quite the opposite.
Oswalt's return last month from back problems gives him ample time to find his old form and seal his fourth spot. Since that return, he's been solid in posting quality starts in five of his first six starts, entering Monday's outing against his old mates in Houston, but he's allowed 50 hits in 40 innings, which is a sign that he's not quite right. According to Fangraphs data, he has become much more reliant on his fastball and changeup this season (his slider and curveball use has dropped about 10 percent from 2010), and his fastball has lost a tick of its velocity.
Experience counts, and managers often side with it in these situations. But Worley has been too good for too long to shrug off.
"Look what he's done," Manuel said last week. "That speaks for itself. That speaks volumes. It tells you how good he's been."
These two rookies, Nova and Worley, have been awfully good on contending teams, and they're not alone. Brandon Beachy might have earned himself a spot in the Atlanta rotation, especially with injury concerns surrounding Jair Jurrjens and Tommy Hanson. Josh Collmenter, whose over-the-top delivery has confused many a batter this year, might be the No. 3 starter for the D-backs, thanks in part to Jason Marquis' season-ending injury.
But in these final weeks of the season, as teams vie for prime postseason seeding and prepare to set their rosters, two powerhouse clubs with healthy rotations will have to take a good, hard look at their starting composition. And in Nova and Worley, the Yankees and Phillies might have two rookies worth leaning on come October.