The Ice Castle Arcade is a time machine.
The Ice Castle Arcade in Backyard Hockey 2005
has retro-style arcade games. Many of the characters say in the first game that the series takes place in the present day. Since the heyday of arcade games was in the 1980s, and most of the pros were children at that time (like they are in the games), isn't this a possibility?
Sunny Day frequently forgets people's names.
This is the reason for the Mad Libs Dialogue
— she keeps having to read the names off of cue cards. Her co-commentators tend to ad-lib, so they don't have the same problem.
The generic filler kids in seasons are seen through the eyes of the Backyard Kids.
The Backyard Kids don't know these people very well, so they are shown through their perspective. They all look the same to the Backyard Kids, so that's what they look like to us. It is a possibility, right?
Hockey through Football 2006 takes place a couple years after the classic games.
Not only are most of the characters redesigned, but some of them look slightly older. For example, Kimmy's Sweet Tooth
got so bad that she's now wearing braces, and Luanne is now using her teddy bear as a backpack. However, Pablo and Dimitri look almost the same.
Also, Basketball/Baseball 2007 might take place a couple years after the Hockey redesigns. Keisha's bio says she still isn't a teen yet, but Vicki is taller and has finally stopped taking ballet lessons.