The word number one started the day seven strokes off the lead and while a two-under-par 69 was credible in windy conditions, it was not enough to lift him into contention at the Boston TPC.
"Today was a bit of a struggle," Woods, who has not won this year while going through divorce in the wake of revelations of marriage infidelity, told reporters.
"Overall today I think I played better than what my score indicated," added Woods, who posted a seven-under 206 total.
"I had a lot of putts that I didn't make today. I made a couple nice par putts, but boy, I missed a lot of birdie putts. I kept getting double breaking putts.
"I had to really grind and stay committed to what I was doing out there. I did it for the most part.
"Early on I was struggling a little bit, but fixed it, got it, and hit a lot of good shots after that."