The Mets’ payroll — more than public statement — often best reveals what team decision-makers actually believe of their chances to win.

Coming off consecutive playoff berths and with what they thought was a powerhouse rotation, the Mets last year set a franchise record for an Opening Day payroll at about $155 million as, notably, they agreed to the largest per-annum contract in their history with Yoenis Cespedes, paid Neil Walker the $17.2 million qualifying offer and did not trade all or part of Jay Bruce’s $13 million salary.

That was not Yankees money, but it was large for the Mets and will dwarf what is coming now. For the opening payroll number will be roughly $20 million less in 2018, a concession that the rotation might never be the powerhouse they hoped it’d be. That realization, in conjunction with other factors, has lowered the Mets’ internal assessment of their playoff chances from this time last year. And, thus, lowered how much the Wilpons and Saul Katz are willing to invest in the roster.

They have not surrendered to a rebuild, banking in particular that Mickey Callaway, Dave Eiland and an upgraded devotion to preparing and monitoring their pitchers will allow the Mets to rebound toward 85-plus wins. But there also will not be a significant offseason splurge. Sandy Alderson has roughly $10 million remaining to spend on free agents or trades and can expand that to a larger amount if he can, say, deal someone such as Juan Lagares or AJ Ramos.

The way the Mets have operated under Wilpon ownership is that the GM receives a general payroll number — this year it will be in the mid-$130 millions, from what I have deduced in conversations with people inside and outside the organization. But the Wilpons then tell their GM to come to them with any deal he likes regardless of cost and sell the merits, and that leaves open the possibility of increasing payroll.

But, again, that sales job is easier to make in years when the leadership believes it has a strong contender.

Thus, Alderson is maneuvering under a tight window the rest of this offseason, which is why after inking Anthony Swarzak, he is in a bit of a financial Four Corners hoping — with many other teams in the sport — that players lower demands in January as they remain unemployed and spring training approaches.

But the reduction in payroll means, for example, the Indians’ Jason Kipnis (owed two years at $30.5 million) will almost certainly be beyond the imposed financial parameters.