Gerrit Cole joined the Astros over the weekend, and it prompted the better part of the baseball world to boldly proclaim that the world champs -- as if not stacked enough -- are now in possession of the best rotation in baseball.

Ah, but dear reader, you and I are calm, rational, open-minded adults, right? We don't fall for in-the-moment enthusiasm or blind and wild speculation. Before we go crazy over Cole, we want to be absolutely certain the 'Stros are all they're cracked up to be in this area.

So let's do a little experiment here, with a big assist from FanGraphs.

Last year, the Indians used the fewest starters in baseball, with seven. That will be our base. I took the top seven FanGraphs-projected Wins Above Replacement totals for each starter on each Major League team and the 2017 FanGraphs-calculated WAR totals those same seven arms provided. I then took the average of the two totals from each list and -- voila! -- there's your Reasonably Objective Theory About Throwers' Impacts On New Season.

Here are the top five ROTATIONS as we sit here today, knowing full well that free agents Yu Darvish and Jake Arrieta (or a trade possibility like Chris Archer) could still swing a club's stats significantly and knowing that major internal improvements (I wrote in here about how the Mets and Cardinals are among the clubs that could be substantially better in 2018 ) can and will move the needle, too.

1. Astros


Cue Barry Manilow singing, "Looks like we made it!"

A few days ago, Houston would have finished second in ROTATIONS, but the arrival of Cole and his projected 3.8 WAR allowed this Astro-nomical ascent to the top spot.

As I write this, FanGraphs' provided projection has not been updated to reflect his change of teams, and perhaps it won't change at all. But the speculation about this swap is that it will ultimately be a good thing for Cole. There is data to suggest that an increase in curveball usage would provide him with better results. One counter to this claim is that if Cole's fastball has as many flat moments as it did in 2017, when he allowed a career-high 1.4 homers per nine, Minute Maid Park is going to be especially unforgiving.

But obviously, if Cole projects to be your third- or fourth-best starter, that's a great group. Combine him with a healthy, walk-year Keuchel, a healthy McCullers and Verlander still hopefully fighting off Father Time, and there's a lot to love here, before you even get to World Series hero Charlie Morton or to Brad Peacock, who, in terms of fWAR, was the Astros' most valuable starter last year (Verlander's 4.1 mark obviously came primarily in Detroit).

2. Indians


Though the Tribe ranks second on a ROTATIONS model built on average of the two totals, you can see here that FanGraphs sees regression for this great group in 2018. It remains to be seen if that's mathematically accurate but it feels emotionally accurate.

As mentioned above, the Indians used only seven starters last season, the fewest in MLB. Those seven starters accounted for 66 percent of the team's total innings pitched, the highest percentage in baseball. So the Indians used less to get more, and that's an awfully difficult equation to maintain over multiple years. Kluber, having battled back from an early back injury to go on a statistically absurd trek toward his second American League Cy Young Award in 2017, sure seemed to be laboring through either fatigue or an injury in his two ugly postseason starts. A run of bad health for Kluber or the others could test the depth considerably, and one of the Indians' more interesting depth options -- 2016 AL Championship Series Game 5 hero Ryan Merritt -- is out of Minor League options and therefore might not even be with the club past Spring Training. That's one reason the Indians have not yet capitalized on the trade value of the oft-injured-but-high-upside Salazar in this marketplace.

Anyway, if everybody's healthy, the Indians are awesome, obviously.

3. Nationals


Given the strong relationship between Nats ownership and Scott Boras, I'm not 100 percent convinced that Arrieta doesn't wind up in Washington, where his projected WAR of 2.7 would, much like when Scherzer was signed, strengthen an already obvious strength.

Why might that be necessary, you ask? Well, for one, it would guard against Gonzalez's pending free agency. Furthermore, we know about Strasburg's injury history, and how he has exceeded 183 innings only once (in 2014). Go back to the start of 2013, and, between the regular and postseason, Scherzer has thrown more innings (1,141 1/3) than anybody in baseball. Does that begin to catch up to him in 2018? And nobody really knows what to expect from that young group vying for the Nats' fifth slot.

But with or without Arrieta, the Nats have a strong group fronted by a three-time Cy Young Award winner and backed by a bullpen that was improved dramatically by the midsummer acquisitions last year.

4. D-backs


Here's a club that provides a firm and necessary reminder that the projections -- yes, even, sadly, our newly created, scientifically savvy and adorably named ROTATIONS model -- can't tell us everything.

A year ago, it would have been difficult to assume that Greinke, given the decline of velocity and the shoulder issues he had endured in 2016, would have as big a bounceback season as he did in his second year in Arizona. And it would have been impossible to assume Ray, who to that point had a below-average 92 ERA+ in 330 2/3 big league innings, would be as big a weapon as he was. But lo and behold, the D-backs had one of the best starting staffs in baseball, and that's a big reason why they pushed themselves into the playoffs for the first time since 2011.

Ray had the second-highest strand rate (84.5 percent) among qualifiers last season, and that can be difficult to maintain, but, as you can see, FanGraphs likes his chances of building on the breakout. The projections are less kind to Godley, a ground-ball guy who got a surprising number of swings outside the strike zone last year. An X-factor here is Corbin, who has garnered trade interest ahead of his free agency at season's end, and it's not out of the realm of possibility that the D-backs do deal him given the budget crunch created by Greinke's outsized average annual value. But if kept together, the D-backs project to be good to go in the rotation.

5. Red Sox, Yankees and Dodgers

These three clubs all wound up with ROTATIONS marks so close that it seemed silly to separate one from the others.

We'll start with the Red Sox…

Red Sox

You didn't need FanGraphs' fancy math to tell you a Price bounceback is elemental to the argument that the Red Sox have one of the best rotations, but here are the numbers behind the notion. Price's iffy elbow invites some skepticism that he can be worth 3.3 WAR. But with effective management of the issue, who knows? Porcello must also be closer to the 2016 AL Cy Young Award-winning model than the 2017 edition, which was responsible for the highest opponents' hits total (236) of anybody in the league. Sale might not be quite as awesome as he was when he struck out north of 300 guys in 2017, but, well, it's easy to assume he'll be pretty awesome.

Here's the outlook for the Yankees …


Another example of the impurity of projections. The Yankees' rotation was loaded with uncertainty going into 2017, but the hard-throwing Severino established himself as their ace up top, Sabathia continued his maturation into crafty veteran lefty, Montgomery was a rookie revelation and Gray was an in-season addition. Even Tanaka, who had a mostly miserable regular season, had a magical stretch in the postseason, leading to optimism that he can pitch like their ace of old.

But it's no secret the Yankees were in on the Cole talks with Pittsburgh, and they've had discussions about Corbin and Darvish and Alex Cobb and others. So this ROTATIONS mark might change.

Last but not least: the Dodgers…


We're limited to listing seven Dodgers here, but if history is any guide, they might use, like, 17 by season's end. Buehler's the most intriguing depth piece here. The high-velocity right-hander is L.A.'s No. 1 prospect, per MLB Pipeline, and though he'll likely begin the season in Triple-A, he could be up in the bigs full-time soon (the obvious hope is that he avoids the same fate of another hot prospect, Julio Urias, who had surgery last summer).

So much of the WAR totals here rightly revolve around Kershaw, and we all know he's battled back issues each of the last two seasons. We also know the Dodgers favor quick hooks that limit the innings and impact of some of these arms, most notably Hill. It's a progressive team, and the makeup of the rotation, which still might see the return of Darvish, is a moving target. But the Dodgers are deep enough -- and Kershaw's projection is still substantial enough -- to round out our ROTATIONS list. 

Now, please, somebody sign Darvish or Arrieta so we can crunch some more numbers!

* * *
Anthony Castrovince is a Sports on Earth contributor, columnist and MLB Network contributor. Follow him on Twitter @Castrovince.