Dear Pepsi,

Are you OK? There can’t be much doubt that things are hoppin’ over at your place these days. Losing 6.3% of your sales in 2010, getting passed by Diet Coke, and dropping to the number three soda overall is not office party material, but I’ll bet it has your juices flowing.

Having openly declared my full admiration for Coke as the greatest brand ever, I suspect I look at your brand sort of the way Fox News treats politics, which is to say fair and balanced some of the time, but not always. But here’s what I see from a branding perspective.

Last year I defended your actions as bold, while you systematically watered down your brand’s packaging with a three-headed logo revision and new bottle graphics that were harder to read. Honestly, I really wanted to see the “Refresh Everything” campaign concept work. It seemed so right for the times, so right for the market. With “Refresh” doubling as your slogan and your brand strategy, you kicked off the admirable Pepsi Refresh Project, which took $20 million from your marketing budget (not the Pepsi Foundation) and used it to fund ideas to help communities. You promoted it heavily in social media and paid advertising.

Presumably it did deliver positive results to many communities, in particular the Gulf region impacted by the oil spill. But it wasn’t enough to lift sales, was it? Likewise, your logo makeover with elaborate design explanations that included Mona Lisa’s smile, symmetrical energy fields, and the gravitational pull of the sun (Google “Pepsi gravitational field” if you don’t believe me) hasn’t helped either.

Your battle with the Greatest Brand Of All Time (there I go again) has been epic and full of twists and turns, most notably the panicked introduction of New Coke. And certainly being a dominant number two brand (oops, sorry, number three) is nothing to be ashamed of. But what really made you great was your introduction in 1963 of the Pepsi Generation concept, which took your brand from being a value challenger with jingles like, “Twelve full ounces, that’s a lot! Twice as much for a nickel, too,” to a much more aspirational concept about living a more fun lifestyle, as in, “You’ve got a lot to live. And Pepsi’s got a lot to give.”

Yes, the Pepsi Generation was kicking cans and taking names and served as the foundation for market share growth that brought your brand to very nearly even with Coke in the supermarket aisle by 1985, although never in fountain sales, and precipitated the New Coke fiasco. But here we are, about another generation later, and your sales are slip slidin’ away.

So here’s my question: Is the Pepsi Generation getting too old for the product? Don’t laugh, it’s happening to Harley Davidson, as the average age of their customers goes up every year. And diet sodas now make up 4 of the top 10 brands by market share, although only Diet Coke is in the top 6 (Current rankings Coke, Diet Coke, Pepsi-Cola, Mountain Dew, Dr Pepper, Sprite, Diet Pepsi, Diet Mountain Dew, Diet Dr Pepper and Fanta.)

It’s like the Pepsi Generation is an idea that can’t hold on, but yet won’t quite go away, either. Here’s an idea for you: Rediscover your brand. Go back to the future. Maybe not in exactly those words, but bring back the youthfulness of the brand you had when Michael Jackson was doing your commercials and the Pepsi Generation seemed just a little more on the edge, a little more vibrant. Be careful, because although everyone wants to feel younger, skateboard grunge isn’t everyone’s idea of youth.

Coke aced you out of American Idol, but you just grabbed a $60 million sponsorship for X-Factor, Simon Cowell’s new talent search show. That’s a step in the right direction, but it’s going to take a lot more horsepower than that to catch Big Red.

I know I’m a Coke lover, but I’m just trying to help. If I wasn’t, I’d encourage you to tell us more about your logo’s Zen connection to Mona Lisa. Look, officially your tagline is Refresh Everything, but until you can find a way to reverse your slide, your slogan is really the apology repeated by about a million waiters and waitresses every day, “Is Pepsi OK?”

And right now, for the company and the cola, I’m guessing the answer is, “No, it’s not.”