On-the-job training can be rough. Just ask the Rockies, who lost 6-1 to Washington Wednesday night at Nationals Park. Rookie right-hander Tanner Gordon, making his seventh big-league start, received a few more hard lessons on a night when the Nats tagged him for five runs on eight hits over four innings. The big blow was delivered by Luis Garcia, who launched a three-run homer in the third inning. He ripped Gordon’s 1-1 slider 419 feet over the center field wall. Gordon is 0-5 with a 7.55 ERA and has served up eight home runs.