You might as well write it in the book right now, judging from this Mike Kiley story in today’s Sun-Times:

Mark Prior declared he isn’t ready to get on the mound, even though the team had said he might throw off the mound Sunday or today.

Prior has stopped even thinking about a possible return date — that’s how uncertain his return is. But he pointed out that he usually takes six weeks of throwing time to prepare for the start of spring training, and he is not even at that stage.

Based on that schedule, it now seems possible Prior might not be recovered from his bouts with right Achilles tendinitis and an inflamed right elbow until late May or June.

“My arm is not in shape yet, not enough to get on the mound,” Prior said Sunday. “I want to get on the mound, but I know long toss is better to get my arm in shape right now. It’s more of a gut thing. I just know it’s not strong enough. It’s not as easy to throw long toss as it usually is.”

Prior again played catch Sunday on flat ground and used a towel to simulate his delivery off the mound. How many more workouts like this before he can get on the mound and actually throw pitches?

“Hopefully, no more than two or three more times,” he replied. “It’s just getting stretched out. I throw from the first week of January to the start of spring training [to get ready to pitch]. That’s how long it usually takes. Hopefully, it doesn’t take that long this time.”

Just getting stretched out? Come on, Mark. We’re not that stupid. The elbow problem is obviously the holdup now, and the rumors swirling are that Prior will need Tommy John surgery.

“When players notice discomfort and changes in their pitching ability,” Jennifer Dawkins of drkoop.com writes, “it is not immediately apparent that something is seriously wrong. Ruptures are detected through a magnetic resonance imaging test, or MRI, sometimes after days or weeks of mild pain.”

Sounds a lot like Prior’s own reports about his elbow stiffness at the end of March:

They said it was like shin splints as far as an injury. They didn’t have any more specific answers except that it was inflammation around the bone. We didn’t know if it was pain getting referred over there and it was pain where I was having discomfort and stiffness and achiness.

Prior will keep long tossing until the elbow magically feels better, which seems unlikely, or an MRI confirms what everyone fears — a torn ligament.

So all bets are off now. This team will still compete, but there’s not much reason to hope for a World Series appearance, much less a championship. And with a minimum of a year from surgery-to-pitching and more like two years before Prior is really “back,” the outlook is decidely dimmer.

The Cubs can still be very competitive in the meantime. After all, they’ve still got Wood and Zambrano, along with some very promising minor-league pitching prospects. Sosa will still be here for a couple of years, Lee has been signed for three years and in the early going Ramirez appears to be showing that he has the stuff to become a long-term solution at third base.

Meanwhile, the end of Moises Alou’s and Alex Gonzalez’s contracts will free up millions to spend in the free-agent market to get much better players.

And if anyone can pitch productively into his early 40s, it’s Greg Maddux.

But the Prior equation is simply this: with him, the Cubs are a powerhouse; without him, they are just “a contender.”