A day after clinching a postseason berth, the Pirates secured a four-game sweep of the Rockies on Thursday afternoon at Coors Field with a 5-4 win — their sixth straight — thanks to a lead-changing three-run homer to right field by Pedro Alvarez with two outs in the eighth inning. With the victory, the Pirates improved to 93-60 and remained four games behind the National League Central-leading Cardinals, who defeated the Brewers, 7-3, on Thursday. Pittsburgh trimmed its magic number to clinch the top NL Wild Card spot to seven. The Cubs, 3 1/2 games behind the Pirates, were idle on Thursday.