The Boston Red Sox suffered a 5-4 loss to the Houston Astros, marked by a walk-off home run from Yainer Diaz after the Sox bullpen faltered again. Starting pitcher Tanner Houck had a strong outing, giving up only two runs over six innings, but defensive errors and bullpen struggles ultimately cost the game. The Red Sox's bullpen has been underperforming, with a 6.91 ERA in the second half and 12 blown saves in 16 opportunities. In response, the team recalled right-hander Greg Weissert and demoted lefty Bailey Horn to strengthen their relief options ahead of a crucial series against the Astros. Meanwhile, the Astros are managing significant injuries to their rotation, with both Luis Garcia and Lance McCullers Jr. sidelined for the season, but they are set to welcome back ace Justin Verlander. As both teams head into the next game, the Red Sox's playoff chances are on the line and the Astros look to overcome their rotation challenges.