Don't underestimate the 3P at all. I think the stats don't tell the true story. There's many a Garmin says that the ascent is closer to 6000 ft and perhaps the figures only account for the PG, Whernside and Ingleborough.
On the climb of all 3 there are downhill sections so the amount of climb is greater than the base to summit figure. There's conversely also uphill sections on the descents!

The cross country section from PG to Ribblehead must also add a fair quantity of ascent - there's a few digs in there.