Los Lobos’ core members have been playing together for almost 40 years. They’ve explored an expansive breadth of songs and styles, but ever since their 1992 masterpiece Kiko, they’ve had a hard time coming up with much. Tin Can Trust may be their most straightforward album in years, but it’s also their dullest. And the shoestring concept — the story centers on a guy trying to make ends meet collecting bottles and cans — is a distraction. Los Lobos remain unassailable musicians, which they prove by effortlessly switching among blues cuts (a cover of the Grateful Dead’s “West L.A. Fadeaway”), traditional Mexican music (“Mujer Ingrata”), and rave-up rock (“Do the Murray”). But besides the soulful title track and the understated but blistering “I’ll Burn It Down,” the songs here rank among the band’s weakest.