MANSFIELD, Mass. — Either I’ve learned how to listen to The Dave Matthews Band, or they had a really good night last night at the Comcast Center. Probably both.

A lot of the DMB aesthetic, as an anonymous Internet sage schooled me, is steeped in South African music (Matthews is a native of South Africa), and if you think of it that way, where each song is a mood that comes, reiterates itself and goes, it makes a lot more sense — you won’t be expecting a musical resolution that isn’t coming. That helped the lazy openers “The Stone” and “Old Dirt Hill” go down — a little, anyway.

As for the good night they were on, a lot of it had to do with the personnel switch they made last month, when touring keyboardist Butch Taylor dropped out and longtime Matthews sidekick guitarist Tim Reynolds stepped in. Reynolds provided a direct rock-influenced kick in the pants of the sometimes-meandering music, whether it was taking an inspired solo on “You Might Die Trying” or a hooky ostinato leading into the jam at the end of “So Damn Lucky.”

That’s not to say that the band’s dreaded excesses didn’t raise their heads occasionally; “The Proudest Monkey” has too slight a structure to support the long jam at its end; “The Dreaming Tree” was a simple song that wasn’t done simply enough and sounded cluttered; “Crush” sounds like a cross between smooth jazz and a Cialis commercial. Even then, though, occasional instrumental highlights at least partially carried them through, like drummer Carter Beauford’s (a monstrous player all night) odd-time hi-hat accents on “The Dreaming Tree” and his busy playing, made tasteful through masterful dynamics, on the otherwise dreary “Grey Street.” And touring trumpeter Rashawn Ross (from Soulive) helped anchor saxophonist LeRoi Moore, who rarely played his trademark soprano saxophone, preferring tenor and baritone.

Just when the jamming (really more like extended soloing; only once, during “Crush,” did Matthews seem truly surprised at the musical direction) became an every-song piece of routine, they hit hard with to-the-point renditions of the guitar-driven “Cornbread,” from Matthews’ and Reynolds’ album together, and the funky “Rapunzel.”

Reynolds provided a shot of momentum each time, finishing the regular set trading mini-solos with bassist Stefan Lessard on the intro to the breakout hit “Ants Marching” and tearing into the second encore, the melodically weary “Tripping Billies” (with a pumped-up Beauford kicking it up yet another notch).

The contrast between the diffidence with which Matthews performs and the enthusiasm with which his fans receive him is still striking, but last night there was a musical frenzy to match. Reynolds, according to our friend the Internet, is still only in the band for this tour; here’s hoping they make it official.

Grace Potter and The Nocturnals opened the show with their trademark mix of influences of Southern rock and classic rock (such as the Neil Young-style creeper “Stop the Bus”), while never quite shedding enough inhibition on songs such as “Mastermind” and “Ain’t No Time” to keep themselves from serious VH1 singer-songwriter consideration. The closer, “Nothing But the Water,” showed some edge, however.

Matthews and band return to the Comcast Center tonight, with Michael Franti and Spearhead opening.

rmassimo@projo.com