MLB

Sabathia building case as Yankees’ best free agent

This might be CC Sabathia’s final season as a Yankee. He has an opt-out provision in his contract at the conclusion of this year and what seems certain is that he will either get his old deal ripped up for a new one with a bunch more money or he will go elsewhere.

But no matter the future, Sabathia has a chance during this year to do something special: put himself into the argument for greatest Yankees free-agent signing ever.

He was brought here for two reasons: To be the ace for championship Yankees teams. And to help lighten the spirit of a clubhouse that had grown musty and constipated. So he already has checked both of those boxes.

But say he adds another ring this year while performing as a Cy Young-ace.

Does that move him from a valuable import to the best free-agent signing in Yankees history?

Because the best of the group — think Reggie Jackson and Goose Gossage, for example — had success, but not particularly long runs as Yankees.

Jackson won two championships in five years with the Yankees and Goose Gossage won one in six years, and both accentuated Hall of Fame careers with their stays in New York. Catfish Hunter won two titles as a Yankee, but just one of his five seasons was elite. Dave Winfield had impressive numbers as a Yankee, but his only title was Mr. May.

Cy Young voting is no perfect gauge to greatness, especially since the award did not exist before 1956 and was not given in both leagues before 1966. So, for example, Whitey Ford’s vote totals are skewed, and Yankees greats such as Red Ruffing and Lefty Gomez never accumulated a single Cy vote.

Nevertheless, the Cy voting does offer some value in highlighting excellence. Sabathia has, after all, finished third and fourth in the Cy vote in his two seasons as a Yankee.

Two other free agents finished in the top four in each of their first two seasons as Yankees: Tommy John, who was second in 1979 and fourth in 1980; and Jimmy Key, who was fourth in 1993 and second in 1994. But neither was the ace of a champion in any of those seasons.

Two other Yankees pitchers have had consecutive years in the Cy top four:

Ron Guidry was first in 1978 and third in 1979; and Mariano Rivera was third in 2004 and second in 2005.

But no Yankee ever has finished in the top four three years in a row. In fact, the only Yankees to finish in the top four more than twice in any years are Rivera (four times) and Guidry (three times).

Overall, Sabathia has finished in the top five in the Cy Young voting each of the last four years, winning in 2007 for the Indians and finishing fifth in the NL in 2008 despite spending just more than half a season with Milwaukee. If he gets that high again, he will add to a historic run and further galvanize his Yankee reputation — whether he stays in pinstripes or not.

Mark Teixeira has a ring, a second-place MVP finish and 230 RBIs in his two Yankees seasons, so he also could become a factor in the all-time rankings for best Yankees free-agent signing. But he just has not been as important as Sabathia these past two years nor does he project as being as vital in 2011. The Yankees have other very good hitters. They do not have another starter like Sabathia.

At this moment, Sabathia is 40-15 (.727 winning percentage) with a 3.27 ERA and four complete games as a Yankee. In that time period, the rest of the Yankees’ rotation is 95-77 (.552) with a 4.96 ERA and two complete games.

Yet Sabathia could further burnish a case for greatest Yankees free-agent signing because the team might need him more now than ever.

The Yankees failed to land Cliff Lee, as they had hoped, and Andy Pettitte retired. Thus, the fall-off from Sabathia to the rest of the rotation feels greater than in recent years. There is great trust in the 30-year-old lefty and great doubt about the rest of the starters.

And the retirement of Pettitte also takes a sage voice out of the clubhouse.

Thus, Sabathia becomes even more vital as a stabilizing force, and not just on the field.

In his two Yankees seasons, Sabathia has demonstrated he can handle that burden, as well. He has brought — as GM Brian Cashman had hoped — a positive influence to the clubhouse. He is inclusive, gregarious and laid back. He treats clubhouse kids and Alex Rodriguez well. His demeanor remains pleasant and his confidence high regardless of any failure by him or the team.

“He keeps the mood light,” Phil Hughes said. “This guy never stresses about anything. He is just solid as a rock. You just take for granted that he is going to win and that he is going to be the same guy every day.” He is what a team craves when making a big-money splurge: Low maintenance, big results, instrumental in clubhouse harmony. One more year of that in 2011 and Sabathia may be able to add to his resume of Cy Young and World Series ace that he also is the best free-agent signing in Yankees history.

Money player

The Post’s Joel Sherman rates the Yankees’ top 10 free-agent signings prior to CC Sabathia, who by the end of this season could make his way to the top of the list:

1. Reggie Jackson: Mr. October, enough said.

2. Goose Gossage: Best ERA in Yankees history (500 innings minimum): 1. Gossage, 2.14. 2. Mariano Rivera, 2.23.

3. Catfish Hunter: Only one truly great year, but the first major free agent was a trailblazer for how the Yanks would do business.

4. Jimmy Key: Was a cornerstone to the Yanks changing from a laughingstock to a champion in the early 1990s.

5. Dave Winfield: Mr. May never fulfilled George Steinbrenner’s ideals, but was a constant star in pinstripes.

6. Mike Mussina: Like Winfield, was never part of a championship as a Yankee, but went 123-72 with a 3.88 ERA here.

7. Wade Boggs: Best Yankee batting averages since Joe DiMaggio retired (minimum 2,000 PAs): 1. Derek Jeter, .314. 2. Boggs, .313.

8. Orlando Hernandez: Didn’t have overwhelming numbers in the regular season, but was a postseason stalwart during the 1998-2000 three-peat.

9. Hideki Matsui: Never Godzilla. But classy and clutch.

10. Mike Stanton: You can argue for Johnny Damon, Tommy John and David Wells, but here is a nod to the stealth MVP of the 2000 World Series (13 up, 13 down, two wins).