an on-the-lam comedy in which our mismatched heroes – one humbled, the other a wiseass, both vintage blunderers – flee the authorities and kingpins alike.

With its playful funk score by Christophe Beck and a plot that becomes a tangle of Elmore Leonard-style mishaps, the film often operates like Soderbergh Lite.

Liman assembles an ace cast of character actors to play the various strands of his small-time Boston crime empire, including Michael Stuhlbarg, Alfred Molina, Toby Jones, Paul Walter Hauser, and – for the full effect – Ving Rhames as a cucumber-cool fixer on the Boston boys’ tail.

The ensemble is so stacked with effortless talent, you barely mind how arbitrary the corruption storyline connecting everyone is.

(Were this an actual Soderbergh movie, it would have a clearer point to make about the intersection of blue-and white-collar crime.

) Affleck and his co-writer, Chuck Maclean, are sharper on the small, farcical details, like a long debate about how much manpower you can always expect behind the wheel of an armored truck.

Rory and Cobby, who never entirely stop bickering, end up yanking the former’s shrink into the action, not so much taking her hostage as giving her some plausible deniability to help a couple of bumbling fugitives.

Continuing her streak of being believable in just about everything – be it a maudlin Oscar grab like 'Downsizing' or quirky sci-fi comedy like 'Homecoming' – Chau sells the predicament of a mental-health professional torn between following protocol and doing what’s best for her client.

Yet her calming presence and on-the-fly sitcom diagnoses (turns out both of these men could use some time on the couch!) underscore the larger problem with 'The Instigators.

' Rory and Cobby don’t seem particularly worried, even when narrowly slipping out of the crosshairs of men who want them dead, and that’s probably because they’re never actually in any danger.

For all its gunplay and explosions and multi-car chases, 'The Instigators' is too committed to its good vibes to flirt with real urgency.

It’s a crime lark so relaxed it practically slips the audience a sedative.

Liman, who ushered Damon onto the action-hero A-list with 'The Bourne Identity' a couple decades ago, finds ways to blow money.

(There’s a climactic heist involving fire trucks that probably cost as much money as the characters are trying to steal.

) But on a whole, 'The Instigators' is closer in chatty, small-scale spirit to the director’s debut, 'Swingers,' with Damon in the Jon Favreau role and Affleck bringing some of the sardonic attitude of Vince Vaughn.

Though packed with familiar faces, the movie really does come down to the clashing personalities of its stars, who bring the familiarity of childhood companionship to a couple of strangers bonding over their escalating bad luck.

With apologies to Ben, 'The Instigators' might be the Damon/Affleck pairing worth revisiting.

Though they’ve appeared in multiple movies together over the years, Matt Damon and Casey Affleck have only just now arranged a showcase for their own lifelong personal/creative rapport.

'The Instigators' casts the two as contrasting screw-ups who go on the run after a heist gone wrong, with a bunch of cops and criminals played by famous character actors in hot pursuit.

Director Doug Liman brings a certain discount Steven Soderbergh energy to the action, but the perennially laidback quality begins to seem like more of a liability than a merit.

This buddy comedy lives or dies on your affection for its stars, offering complementary shades of good-natured Bostonian ineptitude.