Arizona Diamondbacks right-hander Zac Gallen has been gritting his way through some tough, but not unproductive starts of late. He had given up five runs in his previous 11.1 innings over two starts — both of which were sturdy-enough performances to help his club secure wins. But Friday night, against a talented, though admittedly somewhat struggling Seattle Mariners lineup, Gallen fell back into familiarly ugly territory. Ultimately, the Diamondbacks fell 7-6 in walk-off fashion. The right-hander gave up five runs in five innings on eight base hits. He walked one — which came around to score — and gave up three home runs, including two from shortstop J.P. Crawford. The Mariners were all over Gallen through his short outing. And so, the ever-persistent questions remain about Gallen's season , and future.…