Fatigue Cost Me Race Times?

I raced at PNA Champs near Seattle this weekend and all of my times were much slower than last year even though I trained for 11 months straight (Masters swim 3 days/week, weight lifting 2-3 days/week, with some cross-country skiing and biking on weekends). I stopped lifting 2 weeks prior to the meet but I swam up until Thursday before the Sat/Sun meet. Mostly did sprints on the Tues-Thur swims before the meet, about 2k meters all-up vs 3k meters for a normal workout. Plenty of sleep time. But I felt tired during the meet and ran out of energy on most events (200/500 yd free, 50/100/200 ***). Age = 51. Should I have tapered more? I have no idea what caused my fatigue. Thanks for any thoughts. Seattle Jack