You tune into any Met/Yankee game in May, and you'll see kids, families, heads of households, Mothers/Wives, Elderly people that are enjoying their day at the ballpark. You don't necassirly get this from basketball. If you have a product thats segmented to a geo market, and that market isn't even represented by a team in the playoffs- you would be absolutley upset and likely to skip out on advertising with the NBA. With the way the league is set up, every area of the country has equal opportunity to have playoff games. Seriously, 8 teams per conference is very liberal- even more embarrasing for the Knicks to not have been in there in so long
If your running a buisness and have a product that isn't meant for a niche basketball audience (sneakers, fitness, gatorade, clothing), you would be making a bad choice by choosing to advertise on an NBA schedule instead of baseball. Advertisers don't care about the games, they care about where the most people are watching.
This would be different if the Knicks were in the playoffs. Back when the Knicks were a playoff team, advertisers used to fight to get their products to run during Knick playoff games.
This argument works the same for other cites as well. It's a geographic/demographic issue here.