The three heroes of TNT's Peabody Award-winning "Men of a Certain Age" (which returns for the second half of its second season tomorrow night at 10) have taken to defining themselves more by what they aren't (young, energetic and optimistic, to name just three things) than by what they are. And it seems much easier to describe the show that way, too.

It's not quite a drama, not quite a sitcom. There's no obvious TV "franchise" (cops, doctors, lawyers, etc.) to hang stories on every week, nor are there sweeping story arcs or big action.

It's a small show about small moments in the lives of three men who feel their possibilities getting smaller every day. In today's TV marketplace - where executives tend to demand some combination of big, loud and familiar - it feels like something of a miracle that "Men" is still around, heading into the home stretch of its strong second season. (No word yet on a third.) HBO can get away with doing a show like "Treme" that relentlessly, unapologetically focuses on the tiny moments in its characters' lives, but TNT is the home of "The Closer" and "Rizzoli & Isles."

But however it got, and then stayed, on the air, "Men of a Certain Age" remains a tremendous pleasure. It's one of the best... whatever it is you want to call it. (Tonight's episode features a character who's fond of inventing "Italian" words; maybe we can put him on the case.)

The back half of season two actually opens with the possibility of huge, sweeping changes for all three main characters. (I would say that minor spoilers follow, but this is a show that can't really be spoiled, since the plot is always secondary to the small moments.) Anxious gambling addict Joe (Ray Romano) starts getting signals that his ex-wife might be interested in him again. Harried car salesman Owen (Andre Braugher) gets an offer to buy his family's dealership that could get him out from under the crushing responsibility. And eternal bachelor Terry (Scott Bakula) ponders taking a major step forward in his relationship with girlfriend Erin (Melinda McGraw).

But if "Men" actually followed through with all of those big changes, it would become a very different - and probably much less interesting - show.

The guys' lives have changed since the series began, but the changes have been incremental, and in fits and starts. Joe stopped gambling, though he keeps participating in gambling-adjacent behavior, like an odd friendship with his former bookie, Manfro (John Manfrelotti), who's facing down the most dreaded word for men of any age: cancer. Owen now runs the dealership after his father's retirement, but with great power comes greater headaches. And Terry quit acting and took a job working for Owen, but he always seems a half-step away from his old Peter Pan ways.

And it's on that focus on slow growth, fractional changes, and the little moments that come when you've been around the block a time or 20, that "Men" really shines.

An upcoming episode has Owen trying to inspire his fractured, depressed staff by taking over as manager of the dealership's woeful softball team. It starts off seeming like every "Bad News Bears" pastiche you've ever seen, but there comes a point where the level of detail - that Owen, for instance, has to bribe his mechanics to play, while the salesman come gratis - and the specific amount of pressure Owen's dealing with makes it into something both unique, and special. Even as a sucker for an underdog sports story, I was impressed by how funny and ultimately moving the episode was.

The first few episodes of this summer run (I've seen three of the six) are a particularly good showcase for Bakula, as we see just how tenuous Terry's grip on adulthood is, particularly given the rotten foundation he built for himself with decades of partying. (Though "Men" overall seems a weird companion for TNT's new bros-will-be-bros law show "Franklin & Bash," I can imagine a spin-off in 10 or 15 years where Franklin and Bash go in for colonoscopies and lament that they didn't apply themselves more when they were young.)

Again, this isn't a show whose charms are easy to articulate, or to sell to people who have yet to sample it. The performances by all three leads are superb (here's the obligatory mention of just how surprised you might be by the subtle charms and depth of Romano's acting). The comedy is pitched at just the right level to take advantage of these actors and writers (several of them, like Romano, alums of "Everybody Loves Raymond") without undercutting the drama. And the show's insistence on dwelling on these little moments and frustrations gives added power to those times (like the baseball game) when the scale gets just a bit bigger.

You spend time with these guys, and you see what they're dealing with, and you really want things to turn out well for them. So when things do get better - or worse - even for a while, it ultimately matters in a way that it just doesn't a more traditional show, driven by plot or by more overt and frequent emotional moments, or any of the other things that "Men of a Certain Age" decidedly is not about.

What it is about, though, is providing one of the most consistently - albeit consistently low-key - excellent shows on television.

Alan Sepinwall may be reached at sepinwall@hitfix.com