Vanilla, its proponents often insist, is the most popular flavor of ice cream. It may not be exciting, but it&rsquo;s reliably satisfying. </p><p>Rob Thomas, one of the world&rsquo;s foremost practitioners of pop music, operates under the same principle.</p><p>As a solo artist and as the bandleader of Matchbox Twenty, Thomas has been racking up astounding numbers on radio and sales charts since 1996. He treated a capacity audience of about 2,400 to a pleasant performance Thursday at the Midland theater.</p><p>Thomas falls in the earnest tradition of singer-songwriters like Bob Seger, Billy Joel and John Mellencamp. Neither trendy nor fashionable, Thomas&rsquo; songs are more likely to impress bankers than critics. Thomas shared one of the secrets of his success as the opening riff to a song rang through the Midland.</p><p>&ldquo;I like this part, Kansas City,&rdquo; Thomas confessed. &ldquo;It&rsquo;s not too fast and not too slow.&rdquo;</p><p>Indeed, Thomas believes in moderation. His concert, a few minutes shy of two hours, was consistently comfortable. The setlist was designed to keep the crowd subdued. Thomas didn&rsquo;t perform a single song from his work with Matchbox Twenty and only five that aren&rsquo;t included on his two solo albums.</p><p>The night&rsquo;s lone cover, a gentle reworking of Modern English&rsquo;s &ldquo;Melt With You,&rdquo; epitomized Thomas&rsquo; approach. He discreetly removed all of the song&rsquo;s rough edges, rendering it perfectly suited for elevators. The man just can&rsquo;t help himself. That treacly transformation stood in stark contrast to Thomas&rsquo; boldest statement of the evening. Rather than giving fans a straight reading of &ldquo;Smooth,&rdquo; he offered them a marvelously tasteful acoustic version of his successful 1999 collaboration with Santana.</p><p>Even better was his memorable take on &ldquo;Streetcorner Symphony.&rdquo; The original song sounds like a chart-topping hit for a Motown act in the &rsquo;60s or for Chicago in the &rsquo;70s. And on the soulful &ldquo;Lonely No More,&rdquo; Thomas effectively channeled his inner Al Green.</p><p>&ldquo;Give Me the Meltdown&rdquo; married the best bits of INXS&rsquo; &ldquo;What You Need&rdquo; and Blues Traveler&rsquo;s &ldquo;Run-Around.&rdquo; Like much of Thomas&rsquo; material, it&rsquo;s derivative but undeniably delectable.</p><p>Thomas introduced &ldquo;Getting Late&rdquo; as &ldquo;a happy little ditty about death.&rdquo; Although it&rsquo;s scarcely more than a sliver of greeting card sentimentality, Thomas&rsquo; gift for melody and insistent voice transformed it into a genuinely moving song. The trite ballad &ldquo;Ever the Same&rdquo; became similarly effective in Thomas&rsquo; talented hands.</p><p>These superior moments were complemented by Thomas&rsquo; outstanding seven-piece band. Even so, every note seemed scripted. The only moment of spontaneity occurred when a disruption near the stage distracted Thomas. He and his band riffed on &ldquo;Kansas City&rdquo; as security guards sorted out the situation in the audience. Thomas&rsquo; improvisation was compelling. He&rsquo;d do well to loosen up more often.</p><p>Thomas&rsquo; presentation may have been predictable, but it was never pedestrian. Just like vanilla flavoring, Thomas is popular for good reason. Another scoop, please.