Nothing is ever easy with the Pixies, now on their second post-reunion album. Kim Deal has been replaced again, this time by bassist Paz Lenchantin (a decent enough fit). But now guitarist Joey Santiago is in rehab, putting all touring plans on hold. The silver lining is that Head Carrier feels slightly more assured than its predecessor, the godawfully titled and uneven Indie Cindy (2014, which compiled three EPs). Baal’s Back, in particular, bristles nicely with a hint of the derangement of old; Um Chagga Lagga provides more surly punk energy. Elsewhere, Black Francis’s jang-a-lang melodies retain their sheen. But it’s impossible to latch on to any of these songs as evidence of any late-period reflowering.