NASHVILLE, Tenn.

As Ben Zobrist was introduced yesterday on stage wearing a Cubs’ cap, flanked by manager Joe Maddon and GM Jed Hoyer, the Mets were busy at the other end of the Opryland hotel, a few floors above, trying to trade for his replacement.

I was very serious about going there,” Zobrist said of New York. “But I think, in the end, knowing the opportunity to win a championship here in Chicago, that’s the main motivation for me.”

Zobrist also mentioned growing up in Illinois, the importance of the proximity to his Nashville home. If that truly tilted Zobrist to the Cubs, then the Mets were powerless to prevent him, because their four-year offer, a source said, was slightly better than the $56 million for which he ultimately signed.

And honestly, there was no point in going any higher. Maybe the Mets got outflanked by Cubs president Theo Epstein, who enlisted the help of his old pal Brian Cashman to clear infield space by trading for Starlin Castro. But again, that was beyond the Mets’ reach.

So yesterday, the Mets returned their focus to what they could control, and that was retooling the roster for their NL title defense — within reasonable financial boundaries, of course. Instead of eyeing that $56 million as a wadded up ball of cash burning a hole in their pocket, perhaps to be slapped down on the table for a run at Daniel Murphy, the Mets added a pair of switch-hitting infielders, trading Jonathon Niese for the Pirates’ Neil Walker and then later signing free-agent Asdrubal Cabrera to a two-year, $18.5-million contract, a source confirmed, pending a physical.

So much for a Zobrist hangover. The Mets learned late Tuesday night that Walker was available, and by mid-afternoon yesterday, Niese’s eight-year Flushing tenure was over. Niese has a guaranteed $9.5 million left on his contract, which expires at the end of next season, and Walker — also a pending free agent — – will likely earn between $10-$11 million through arbitration.

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That was essentially a wash, and with the Mets feeling flush, they agreed on the deal for Cabrera a few hours later, adding another $8.5 million to the ’16 payroll. The Mets won’t have Murphy or Yoenis Cespedes back from their World Series team, but yesterday’s moves will recreate another key element that helped propel them to the NL title: lineup flexibility.

We’re not talking Gold Glovers here. But with Walker at second and Cabrera at short, that gives the Mets a power-hitting middle infield, not to mention depth as long as Wilmer Flores and Ruben Tejada remain on the roster. Just think back to last season, how the Mets’ offensive profile immediately changed once Sandy Alderson pulled off the July 24 trade for Kelly Johnson and Juan Uribe — to go along with the promotion of Michael Conforto.

Better to have more experienced bats than less, even if it was the Cespedes swap a week later that eventually put the Mets over the top. Obviously, the Mets have yet to come up with a substitute for the intimidating Cespedes. But allowing Terry Collins to play matchup on a daily basis will again be critical, along with the capability to rest David Wright whenever necessary due to the chronic back issue that limited him to 38 games this year.

Once Cabrera was in the fold, that ’16 blueprint — now adjusted for losing out on Zobrist — became clear. We figured that once Zobrist fell through, the Mets would regroup, see where the market went for Murphy, and then move.

But yesterday’s rush to secure both Walker and Cabrera told us everything we needed to know about their view of Murphy. Murphy caused plenty of on-field headaches, but he also showed the mettle to survive the darker periods, and provided an October for the ages when the Mets returned to the Series for the first time since 2000.

@Newsday

What a difference a day can make.