This is, I think, the best advice. My default is a nice dark (and freshly-ironed) pair of jeans and a sportcoat. Dress shirt, no tie. It's a good mix of professional and casual. You take the jacket off in the pressbox so you don't get hot, roll up your sleeves to work/type, and you roll them down and put the jacket on when you go down for interviews. I'll wear a tie to the Kentucky Derby and Super Bowl, but usually the no-tie, sportcoat look is a solid bet for anything unless it's 99 degrees.
I respect you good dressers but when the coaches of teams are wearing golf shirts with the team emblem they are setting the standard for it being casual casual casual. With all their rules and such restricting access, why would you get dressed up for a football game on a 99 degree late summer afternoon? Now winter sports like NBA or college basketball or NFL, yeah you wear dress slacks and button down shirt or sportscoat no tie like u said. But college football in the summer? Crazy to not go casual.
Golf shirts? Collars? What is this? 2007? I'll take a dri-fit Nike T-shirt, or some variation thereof. Still can tuck so you don't look like a Neanderthal, but collars are for loserz.
Don't dress to be memorable. That's the advice I give now to folks at my university that are going on camera, if they ask. Clean and professional really isn't memorable, if you're doing it right.
You guys act like we're in the stone age. Sports coats? Ties? Slacks? Give me a fuckin' break. Are we back in the '20s and punching our shit out on a typewriter, too? WTF. Times have changed. Dress the way that makes you look good, feel good and what is comfortable for your environment. My employer has one dress code: dress similar or comparable to the people you cover. As far as what "future employers" and "networking" people you meet might think, I don't give a shit how you're dressed so long as you're not an eyesore. At the same time, I do give a shit how you write. Over time, people aren't going to judge you on how you dress, but they sure as hell will on how you write. Wear blue jeans for all I care but get the damn story and make it sing like Smokey Robinson. You do that, you'll never hear a word from me.
I don't think anyone is arguing what you wear is more important than your writing ability. But I do think it's noticed, good and bad, what you wear in the press box. If you dress like a schlub, people are going to think you are a schlub. To answer the initial question: Wear a polo or button down, dress pants or nice jeans and clean, closed-toe shoes. Don't wear flip flops.
If you hit the bar with the other writers after the game, don't forget your fedora. It's drinking wear.
I've seen a lot of guys that "dress like a schlub" that could write circles around the guys that were dressed to the nines. Who do you think had my respect?