It has been 21 years since baseball found itself in a mess like this. But here we are.

Could two decades of labor peace be just hours away from unraveling? We regret to report that’s a possibility, as the sport goes tick-tocking toward midnight, when its current labor agreement expires.

Multiple sources report there was progress at the bargaining table Tuesday, but what happens if midnight comes and goes, and no new deal has been agreed to? Let’s do our best to answer that question -- and all those other questions you wish you didn’t have to ask about baseball’s latest labor snafu:

If there’s no deal by midnight, what happens?

Still too soon to say. Depends on how much the two sides can build on the progress they made Tuesday. If they’re making headway, they could agree to extend the current agreement for a day, a week or however long it takes. But (cue the horn section) if no deal is in sight, the owners have made preparations to impose a lockout, effective immediately. As of Tuesday evening, no vote had been scheduled by owners to authorize a lockout. But that’s the only real good news. Sources say there is still significant ground to cover. So this could go right to the wire.

If owners lock out the players four months before Opening Day, why is that a problem?

It’s not a big problem when you compare it with past baseball work stoppages, when actual games were canceled. But a lockout, even in December, carries lots of consequences, and none of them are good.

A lockout means a total freeze on offseason baseball activity. No trades. No signings. No designating for assignment. No Rule 5 draft. Beyond that, it means clubs will stop funding all player benefits, including medical benefits. And players would no longer be able to work out at MLB facilities. So who knows what negative forces a lockout could unleash?

But maybe worst of all, a lockout sends a horrible message to fans. If a $10 billion industry can’t solve basic issues without a work stoppage, at a moment in time when the sport is at its highest point in popularity in years, why should fans buy into what seemed to be a bright future?

Will the winter meetings still take place next week even if there is a lockout?

The minor league portion of the winter meetings would go on as scheduled. But no major league teams are expected to attend. And as we mentioned, trades and signings aren’t allowed during a lockout. So unless you’re a big fan of the annual baseball job fair, you wouldn’t have much reason to pay attention.

What are the big issues standing in the way of a deal?

The players have pushed for an end to the system that forces teams to give up a No. 1 draft pick if they sign a free agent who has turned down a qualifying offer. Sources say the owners are willing to agree, but naturally, they want something significant in return.

For weeks, owners have floated the idea of an international draft as a means to control bonuses for foreign-born players. But multiple sources say they backed off that demand in the past 48 hours, and are willing to substitute a revised system involving bonus pools that teams would not be permitted to exceed.

So there were increasing indications that the biggest obstacle to an agreement will be changes to the luxury-tax system. It’s believed the sides remain far apart on how much and how fast to raise the current tax threshold of $189 million -- and on what the tax rate would be on teams that exceed it.

USA Today reported Tuesday that owners don’t want to raise the threshold in the first year of the agreement, and would like to increase it incrementally in future years. Players have asked for an immediate increase that reflects the sport’s steep rise in revenue over the past several years. So it would seem hard to believe that, with so much at stake, the sides can’t find a way to meet somewhere in the middle. But there are other moving parts, so anything is still possible.

So is there any reason to believe they can avoid a lockout?

If you just go by how long it took for any sign of progress at the bargaining table, you would have no reason to feel encouraged by any of this. Yet a number of people around the sport found reasons for hope Tuesday, just by asking themselves the ultimate $10 billion question:

Are these issues really worth shutting down a sport over?

And that answer, basically, is: Hell, no.

This isn’t 1994, when owners were trying to force a salary cap down the players’ throats. These are just fundamental business issues that revolve around how to run one of the most lucrative industries in sports. So in all corners of the game this week, most people have continued to express optimism that eventually, common sense, a spirit of compromise and that all-important instinct for self-preservation will rescue this sport from a mess of its own making.

But while that optimism was growing Tuesday night, it was still far from unanimous. So as the clock ticks, talks continue and 21 years of labor peace hang in the balance, no word better describes the mood around baseball than this:

Nervous.