The resurgent Houston Astros traded for Oakland A's left-hander Scott Kazmir on Thursday, kicking off a weeklong march to the July 31 deadline still teeming with gridlock because of persistent questions about which teams are buying and selling. The 31-year-old Kazmir, struggling in an independent league as recently as 2012, joins an Astros team in need of pitching depth as it tries to catch the red-hot Los Angeles Angels, who surged to the American League West lead on the back of a seven-game winning streak. For two months of Kazmir, a free agent-to-be, Houston sent Class A right-hander Daniel Mengden and catcher Jacob Nottingham to Oakland.