So why did Langford lose...

First of all, Wills was a damn good fighter. If Dempsey didn't duck him, he might have been known as one of the better champions in history.
Second, as you pointed out, there was a big size difference.
And third, Langford had been in a lot of fights, had an eye problem and was past his best.

 

Don't forget too, that Langford was not really a natural Heavyweight., and Wills was a full sized (especially for that time) big guy.

 

Because, A. Langford was over the hill for most of their fights, and B. Wills was a top-notch fighter in his own right.

 

Wills was a great big fighter and at his best. Langford was a great small fighter and at the end of his run.

I think the consensus is Wills was unlucky, he didn't get the Dempsey fight and he came about the end of a great era. On paper Langford should be rated highly, in turn Wills should be rated pretty highly too. Say top30.

 

Also it is a moot point how many fights Langford lost.

He definitely won two (knockouts)

He probably lost six

The rest are a bit ambiguous.

 

They do.

The series was however prety even for the first five bouts with the only knockout wins coming to Langford.

Beyond that Wills was arguably putting the stamp on Langford's decline.

 

The deterioration that comes with aging would appear to have something to do with it.

 

Harry Wills vs Sam Langford

1914 - Wills - DRAW - Both Prime - Wills - 210 - Langford - 187
1914 - Wills - Lost KO 14 - Both Prime - Wills - 210 - Langford - 190
1915 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Wills - 205 - Langford - 195
1916 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Wills - 210 - Langford - 190
1916 - Wills - Lost KO 19 - Wills Prime - Langford - Post-Prime
1916 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Wills - 204 - Langford - 195 - Wills Won Easily
1916 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Wills - 215 - Langford - 204 - Langford Down in Round 2
1917 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Both appeared to be throwing what they called Creep Puff Blows, clearly not wanting to hurt each other.
1917 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Wills - 203 - Langford - 198
1917 - Wills - Won UD - Wills Prime - Langford - Post-Prime - Wills - 203 - Langford - 196
1918 - Wills - Won KO 6 - Wills Prime - Langford - END - Langford took a Severe Beating, Sam was going blind & also going downhill overall very quickly.
1918 - Wills - Won TKO 8 - Wills Prime - Langford - END - Langford took another Bad Beating
1919 - Wills - UD - Wills Prime - Langford - END
1919 - Wills - UD - Wills Prime - Langford - END
1919 - Wills - UD - Wills Prime - Langford - END
1920 - Wills - UD - Wills Post - Prime - Langford - END
1922 - Wills - UD - Wills Post - Prime - Langford - END

Wills - 14-2-1 Overall
Wills - 0-1-1 with both in Prime

 

too many langford Jock sniffers just as their are for Aaron Pryor, although Sam deserves a lot more praise than Pryor, it's just that they've overdone it, they say if you pick anyone that beat Sam, he was too old, he was blind, he was this or that, it's always excuses for him without the hard evidence to back it up, they only want to rely on his Wins, he was a great fighter that's obvious, how great we will never know, their were other great black champions, so why he was never one, don't always claim Race as the issue, sometimes yes, others, no, he just never got a title, so yes that hurts him, you can't build him up like he had several, maybe there was other reasons he never won a title, Wills beat a couple of solid fighters at an advanced age and was the #1 contender when well past his Prime, and won a lot of fights then, he had no excuses.