Norris has pitched very well against the Pirates in his career, striking out 65 batters and walking just 15 in 55 innings. He also shut them down completely in early May, allowing no earned runs while whiffing eight batters in six innings.
There's reason to hope things might be different this time, though -- none of the Pirates offenses Norris has faced have been as potent as the one that's been carrying the Pirates for the past month. He's also struggled with home runs, allowing seven in his last four starts, and the Bucs' offense has hit home runs by the bushels recently.
Karstens struggled in his return from the disabled list on June 25, allowing six earned runs in five innings against the Phillies, but he rebounded to whiff seven in seven innings against the Cardinals.