If you listen to Phillies fans, Patrick Corbin is either going to be a left-handed ace capable of pushing a team over the top toward contention, or a decent but replaceable starter whose arm is going to fall off three years into his new contract. It all depends on when you asked them: before the Nationals signed him to a six-year $140 million deal, or after, when he was no longer in play for the Phillies.

Regardless of the wisdom of the deal, Corbin’s signing does benefit the Phillies by providing to them a benchmark of sorts for the rest of the offseason as they consider the optimal way to construct their own rotation for 2019 and beyond. It’s all well and good to abstractly label a pitcher a No. 1, a No. 2, a No. 3 starter, but that kind of exercise is a lot more constructive when you make those assignments within the context of an actual series. For instance, given that the glasses are always rose-tinted this time of year, you might be tempted to label Jake Arrieta a legitimate No. 2 or No. 3 starter behind Aaron Nola. He might not be the top-of-the-line No. 1 that he was for a few years in Chicago, or that Nola is now. But the 32-year-old righty is coming off a season in which he posted a 3.96 ERA 172 2/3 innings with average-ish strikeout numbers, and you can definitely talk yourself into thinking that the stuff of a No. 2 starter.

That is, until you consider the fact that he would be matching up against Corbin or Stephen Strasburg in Game 2 of a series against the Nationals. The first option finished 2018 with a 3.15 era in 200 innings while striking out 1.5 more batters per nine innings than Arrieta ever has. As for Strasburg, the innings have not been there over the last four seasons (average: 145), but he is still coming off a year in which he struck out 10.8 per nine (Arrieta: 7.2) with very good walk and home run numbers.

That’s not to say that the Nationals are suddenly the National League favorites. We’ve seen the Super Rotation movie before. You may remember that it does not often end with a fade out over a parade. The Nationals themselves would be hard-pressed to replicate the pitching staff they featured two seasons ago, when Gio Gonzalez was the lefty third wheel putting up numbers comparable to the ones Corbin posted in Arizona. They had three starters finish with 175+ innings and sub-3.00 ERAs, and that October still ended the way all of the previous ones have: early.

Likewise, in 2017, the Cubs added Jose Quintana to Arrieta and Jon Lester, and the Dodgers added Yu Darvish to Clayton Kershaw, Alex Wood and Rich Hill, and none of them ended up winning a World Series.

On the flip side, all of those teams experienced considerable success, much more of it than the Phillies have at any point since 2011. So while Matt Klentak and Boss Moneybags showed justifiable restraint in refusing to pay Corbin $23 million a year through his 34th birthday, they also surely realize entering a season with Arrieta as a No. 2 and either Vince Velasquez or Nick Pivetta as a No. 3 would constitute a borderline untenable situation.

When Klentak held a conference call for reporters on Monday evening to discuss the Phillies’ trade for Jean Segura, one suspects that he already had an informed inkling that Corbin would be suiting up somewhere other than Citizens Bank Park next season. Asked if he was optimistic about landing a pitcher this offseason, he responded, “Am I optimistic? That’s hard to tell.”

“I can tell you this,” the general manager continued. “We are open to the idea of adding to our rotation, particularly in the form of a left-hander to create more balance on our pitching staff. Whether we’re going to line up with a free agent or a trade partner to make that happen, I’m not sure. It’s not a secret. We’ve been talking to several pitchers. We brought one in here last week for a meeting. We’re definitely exploring that path.”

Assuming that Corbin’s ultimate decision was one of dollars and cents, the fact that the Phillies declined to beat the Nationals' bid would seem to suggest that they are at least moderately confident in their ability to add an arm that is qualified enough to start Game 3 of a series. Frankly, if their goal was to make this roster playoff-ready tomorrow, they’d be wise to consider adding two arms, given the potential of further regression by Arrieta and the fact that neither Pivetta nor Velasquez established himself as that kind of pitcher last season. While Pivetta showed significant improvement over his rookie season, he posted a 6.10 ERA over his last eight starts while finishing more than five innings in just one of them. In a perfect world, Pivetta would enter the season as the No. 5 starter with Velasquez in the bullpen.

As it is, one arm will do. From a free agent like J.A. Happ to trade candidates like the Diamondbacks' Robbie Ray and the Giants' Madison Bumgarner, the Phillies have plenty of options. Doing nothing is not one of them.