I think people are misunderstanding what this award actually means.
The 3 main individual awards in this country are -
- The PFA Players' Player of the Year award. This is awarded to the best individual the other players feel has given them the hardest game.
- The Premier League Player of the Season, which is supposed to be unbiased award - from the league itself - to its best individual performer.
- The Football Writers Association Footballer of the Year, which is decided by a bunch of storytellers to the one character who's given them the most interesting narrative over the course of the season.
Nobody thinks that Henderson is the best player in the league. That's kind of what the other two awards are about. But journalists obviously reckon he's been the most compelling subject for their articles: a largely unsung player; derided by the fans for years; made huge improvements to his game in recent seasons; has now become mister reliable; took on the captain's role that everybody said was too big for him; did the one thing Gerard never could do by giving his team a title they've been chasing for 30 years; and on top of that, he led the league's players in its response to covid-19.
If you were writing a movie based on one player this season, Henderson would certainly make an interesting subject. And that's what the award is for. It's a bit like the Sports Personality of The Year in that regard - not just about the sport.
You could argue there's a bias from the sheer number of Liverpool fans in the media (and Guardiola has done precisely that). But that's just one of those things you have to deal with. Writers are always going to want to write about the things they're most passionate about. If that bothers you, ignore the whole thing.