"just to be clear, are these #s over the course of the race (seems likely but...??"
WDFH - to clarify your question and to give the OP some more info, one of the top-5 riders for this specific race podium usually has his power meter on his race bike shown for his Strava rides and is accurate with his input parameters. For this race - the power curve data was the Strava "estimated" values, no actual power meter data. For reference - the rider is 59 yrs, weight is 160 lbs, and height is 6 ft. 1 in.
For this specific race (51.2 miles, 3200 ft. of climbing, relatively flat for an mtb event), the Strava "estimated" power data was the following from the curve:
1 min - 6.06 watts/kg (440 watts)
5 min - 4.67 w/kg (339 w)
8 min - 4.62 w/kg (335 w)
10 min - 4.57 w/kg (331 w)
20 min - 4.28 w/kg (311 w)
1 hr - 3.66 w/kg (265 w)
2 hr - 3.39 w/kg (246 w)
FWIW: Using the 8 min value from the race data and recognizing that this is from the Strava "estimated" power curve, the estimated training FTP would be 4.2 watts/kg. He did not win the race by any means - but for 59 yrs old (soon to be 60) is considered one of the top riders in this area, is always on the podium, and is in the 50+ Age Division. He trains diligently 11 months of the year, races the longer endurance xc races such as 4, 6, 8, and 12 hr events, including the Breck Epic, Park City P2P, BC Team Stage, Leadville, SoCal Endurance Series.