They signed within days of each other last December for more money per year than any pitcher had ever received. They left first-place teams but didn't leave their division, both joining sub-.500 clubs itching to win.
Now here we are in March, trying hard to figure out which team did best and which super free-agent ace will do best.
This isn't about length of contract, how Greinke will do when he's making $35 million in 2021 at 37 years old or how Price will do when he's making $32 million at age 36. No, this is strictly about 2016, because when it comes down to it, the Red Sox and Diamondbacks spent all that money for an instant return.
The easy answer is they both will get it, because Price and Greinke both have the talent and the history and the personality to justify the huge belief their new employers showed. But you don't come here for easy answers.
If the question is which one will have a significant impact, the answer can and should be "both." But the question is which one will have the bigger 2016 impact, and the answer is David Price.
Some of that has to do with him. A lot of it has to do with the team he joined.
It's true the Red Sox were a disappointing last-place club in 2015, while the Diamondbacks were seen as a third-place team on the rise. But it's the Red Sox who are better positioned for a big 2016 jump, especially in the wide-open American League East.
"Strong and deep," one Fort Myers-based scout said this week when asked for his early impressions from Red Sox camp in Florida.
The starting pitchers behind Price remain a real question, but one of the reasons Price was attractive to Boston is his history of being able to lead a rotation. In fact, if you want to see how much impact a true No. 1 starter can have, the 2016 Red Sox should be a nice case study.
Greinke has some of the same abilities, but his personality makes him less of a natural leader. He should pitch well in Arizona, but will he lift the other starters as much as Price could in Boston?
Even if he does, will the Diamondbacks bullpen be able to hold the leads?
Scouts and executives surveyed by Bleacher Report saw Greinke as the starter more in need of a solid bullpen, but they see the Red Sox bullpen as far superior to the one Greinke will have with the Diamondbacks.
"Price can throw nine innings in his sleep," one scout said. "He'll get to the eighth inning a lot more and give the ball to [closer Craig] Kimbrel and the setup guy. Greinke will get a lot of no-decisions in Arizona, and he'll get frustrated because he wants to win."
Greinke has just two complete games in the last five seasons combined. Price has 12.
To be fair, Greinke actually finished seven innings more times last year than Price did (21-19). The point still holds, though, because seven innings from Price gets the ball to Koji Uehara and Craig Kimbrel, while seven from Greinke gets it to Tyler Clippard and Brad Ziegler.
Some scouts surveyed by Bleacher Report did favor Greinke, mostly because pitching in the National League West should help him put up better numbers than Price can manage in the American League East.
But the AL East also presents Price with opportunity because the Red Sox look better positioned to win their division. The Diamondbacks had a good winter, but so did the San Francisco Giants, and even without Greinke, the Los Angeles Dodgers remain a strong threat.
Which starter will have the greater 2016 impact?
"Greinke could pitch well, and the Diamondbacks could still be a .500 team," one rival executive said. "If Price pitches well, the Red Sox could win. If he doesn't, they don't win."
For now, both teams seem happy with their big-ticket purchases. Price has made the expected good first impression with the Red Sox, and Greinke has done the same with the Diamondbacks.
Greinke's first spring start got big coverage. So did Price's simulated game last Saturday.
The attention will only grow as Opening Day nears for two pitchers who were paid big money to pitch that game and many big games to follow. They are getting that money for big impact, and there's a real chance both will deliver.
The guess here is Price will deliver just a little bit more.
Danny Knobler covers Major League Baseball as a national columnist for Bleacher Report.
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