Allman Bros, showrock's strengths,By ALLEN JONESWAmusrmrnts WriterThe Allman Brothers' concertFriday at Hofheinz Pavilion readlike a checklist of the strengths and weaknesses of rock musicThere were professional musicians and dismal amateurs, excellent music and noise Wet Willie opened the evening like somebody tumbling off the wrong side of the bed Falling prey to every rock 'n' roll cliche conceivable, their set was highlighted by hokey showmanship, awful arrangements and worse playing The only member of the band showing a modicum of talent was the singer, who doubled on harmonica and saxophone. He displayed a fair voice, but was far too given over to endless shouts of “(h. yeah” and exhortations of “Does everybody feel all right?”to be very effective.After whipping the crowd into a frenzy Wet Willie climaxed theirshow with a blues concluded by the singers' invocation to some personal goddess, “Well, if you take care of my hot dog, baby,why I II take good care of your bun.”The resulting encore brought guitarist Ricky Hirsch onstage to trot out his favorite licks and prove that he's about as flashy as a tree stump.Houston was treated to its first sight of Gregg Allman on the guitar when the Allman Brothers opened with his composition “Midnight Rider ”Bond shifts to high gearA couple of songs later he switched back to organ and as the strains of “Statesboro Blues” bathed the crowd, the band shifted into high gear.The Allman Brothers haven’t switched their repertoire much since Duane Allman died in a motorcycle accident a couple of years ago But Friday night was the first time they ever played “Les Brers in A Minor” in Houston.The loss of guitarist Allman and bassist Berry Oakley (who died in a similar motorcycle mishap that cancelled the Brothers scheduled gig with the Grateful Dead in November) spotlights a few things not evident before.One of these is the over-simplicity of drummers Butch Trucks and Jai Johanny Johann-son They almost always opt for a simple beat, even when a more intricate one might be more effective.Another thing is the brilliance of guitarist Dickey Betts. Although he still owes a great debt to the licks and conceptions of Duane, he is beginning to play in a more distinctive style. His slide playing has improved immeasely since his last appearance here, further dispelling the Duane Allman-protege image.Singing lead on a few tunes, his countryish voice provides a welcome change of pace from Gregg Allman's blues inflections. His songs are also a refreshing change from Gregg’s more progression-based songs.There have been many changes in the Allman Brothers Band Newcombers like pianist Chuck Leavell emphasize this as much with their additions as theirdetractions.*Gone are the harmonic lead solos, the musical interplay and the stunning jams. But the Allman Brothers remain and play on.GUITARIST DICKEY BETTS of the Allman Brothersstill owes a debt to the late Duane Allman for his guitar licks. But he Is beginning to play in a more distinctive style, as evidenced by his performance Friday night withthe band in Hofheinz Pavilion Photo By TERRY PROPST