For the most part it was a result of driving the ball into trouble , which was always his nemesis ( he just recovered better than anyone else). This was a very forgiving course off the tee and Tiger only hit 55% of fairways. He struggled more on the back nine ( as did the entire field) where the wind was more hurting, the wind accentuates swing flaws and errors.
I'd hazard a guess that his mental and physical stamina wasn't there after the layoff. Likewise though for all the other players this event was the last in a very long season so they would be fatigued and drained , looking forward to their brief break and probably not at their best either .
overall a good return -4 over four days so averaged under par each day, and as I've said, better than most ( probably Tiger too) expected. Iron play and putting were really good.
The biggest takeaway, he played injury and pain free and was taking some huge rips at the ball in round 4. Will be interesting to see how he does at Torry Pines