Source: Johnny Cueto turned down 6-year $120 million offer from #Dbacks https://t.co/zX6gqL6Asv

— Steve Gilbert (@SteveGilbertMLB) November 30, 2015

It's not surprising that Johnny Cueto would turn down the Diamondbacks' offer considering it's less money on an average annual basis than Jordan Zimmermann just agreed to with the Tigers (five years, $110 million) and Cueto is the better pitcher and the same age.

But is it possible that's the best offer Cueto receives? Even though only Clayton Kershaw has a better ERA among starting pitchers since 2011, Cueto's free agency comes with a couple of red flags: his struggles with the Royals after coming over from the Reds (he posted a 4.76 ERA in 13 starts); and a tender elbow that twice caused the Reds to give him extra rest between starts before trading him (he went from May 19 to June 2 without pitching, which was the longest layoff). While an MRI in May revealed no structural damage to his elbow, the medical records will certainly be a huge factor in Cueto's next contract.

The more difficult assessment for teams will be analyzing what happened with the Royals. Cueto did at least regain some lost luster with two strong starts in the postseason -- eight innings of two-run baseball against the Astros and then a complete-game two-hitter against the Mets -- although those were sandwiched around an eight-run blow-up against the Blue Jays. His wOBA allowed in the postseason was actually higher than it was during his 13 regular-season starts with the Royals:

Reds: .223 wOBA allowed

Royals regular season: .314 wOBA

Postseason: .351 wOBA

Here is Cueto's wOBA allowed in the regular season against each of his pitches with the Reds (left) and Royals:

Fastball: .223, .314

Cutter: .281, .419

Changeup: .301, .345

Slider: .287, .476

Was it mechanics? Location? Stuff? Something related to the elbow? During that rough five-start stretch when he allowed 48 hits and 30 runs in 26.1 innings, his cutter in particular had flattened out with little to no movement. Cueto did have some bad luck with BABIP, but he was leaving pitches up in the zone too often. It wasn't just the cutter; his fastball and slider were also much less effective. With the Reds, he had a 17.5 percent strikeout rate with his slider; with the Royals, it was just 2.6 percent. The strikeout rate on his fastball went from 22.4 percent to 15 percent.

So teams will be watching a lot of video on Cueto besides checking those medical records. My guess is that American League teams will be more hesitant to sign him after his poor results with the Royals, so my five top potential destinations are all National League teams:

1. San Francisco Giants

Buster Olney wrote in his blog today that six teams -- the Diamondbacks, Dodgers, Giants, Red Sox, Cardinals and Cubs -- are "prepared to spend significant money on a starter." And that assumes the Tigers are done after getting Zimmermann, which may not be the case (since they have a protected top-10 pick, they lose only a second-round pick for signing Zimmermann, which means signing Cueto would mean forfeiting their third-round pick). With one of the top four starters now off the board, that leaves Cueto, Zack Greinke and David Price.

While the Giants need an outfielder, it's more likely they spend big on a pitcher, and there's money in the budget with Tim Hudson and Tim Lincecum off the payroll. The rotation ranked seventh in the NL with a 3.95 ERA ... a mark that rose to 4.76 on the road. It simply wasn't a playoff-caliber rotation in 2015. With Hudson retired and Lincecum and Ryan Vogelsong free agents, that's 59 starts to replace just on a physical level, let alone a results level. The Giants haven't shied away from acquiring pitchers with physical issues in their background -- see Hudson and Jake Peavy -- and if they lose out on Greinke and Price, Cueto has the most upside of the remaining starters. On the other hand, considering Matt Cain's health issues after signing a big contract, the Giants may want to bet on a better health risk like Jeff Samardzija or Mike Leake.

2. Arizona Diamondbacks

The feeling is the D-backs have the position player core to contend in 2016, but they need to add at least two starters to a rotation that posted a 4.37 ERA in 2015, 11th in the NL. Remember: The five NL playoff teams ranked one through five in rotation ERA. In 2014, the five playoff teams ranked Nos. 1, 2, 3, 5 and 9. In 2013, the five playoff teams ranked Nos. 1, 3, 4, 5 and 6. The road to the NL postseason starts with a strong rotation.

So Cueto reportedly turned down $120 million. It doesn't mean the Diamondbacks won't raise that offer. With only Paul Goldschmidt and Yasmany Tomas signed past 2016 -- and Goldschmidt making relative pennies for an MVP-caliber player (he tops out at $14.5 million in 2019) -- the D-backs have lots of payroll flexibility to throw more cash Cueto's way.

3. St. Louis Cardinals

With Lance Lynn undergoing Tommy John surgery and John Lackey a free agent, the Cardinals are looking for rotation depth. I don't see them spending the $200 million it will take to sign Price, and most still think Greinke ends up back with the Dodgers, so that should put Cueto on their radar, especially if they don't re-sign Lackey.

4. Los Angeles Dodgers

Cueto would be more of a backup option if Greinke signs elsewhere.

5. Washington Nationals

Olney didn't list the Nationals as a team looking to spend on pitching, but they surprised everyone with Max Scherzer last year, and with Zimmermann now officially gone and Stephen Strasburg a free agent after 2016, they could be the dark horse who swoops in and gives Cueto $140 million.