Well. You might want to ask one of the other guys this one too - maybe the reformed player, as he is a lot more subtle than I am. My way of dealing with a problem is nearly always to attack it head on until it surrenders abjectly and unconditionally.
But since you asked me first:
Shyness is a horrible, crippling condition, that has to be handled carefully, by whacking him between the eyes with the biggest hammer you can find until he sees the obvious. You'll be the one making the running here - sorry about that. I know a lot of ladies still think that is unfeminine, but it is the way it must be in this case.
I'd just tell him. Don't drop the L word just yet! He'll run like hell even if he feels the same way! Use "really attracted to" instead, and tell him you are lonely. The lonely bit first, it sets up a certain sympathy and sets the stage. And speaking of staging -
Tell him somewhere public, a restaurant, for example, after you have ordered, but before your meal arrives. His shyness, and reluctance to making a fuss, will work in your favor by holding him in place. Then the meal itself gives him time to get used to the idea and kick it around a bit in his mind. A shy guy is shy for a reason, usually because he feels he has nothing worth offering in any situation. That is a hard mindset to crack, never mind break.
Be patient. Good luck. To both of you.
Oh, for the love of all that is functional, don't tell him that you're lonely. Almost every guy who has told me he likes me sets up that "lonely" bit, and it's just resulted in my developing a huge complex and paranoia about lonely guys.
Works different when a woman does it. Trust me.
How so?
In this case she is dealing with a shy guy. One who hides himself, for whatever reason.
Every guy has a bit of white knight inside him, desperate to do something heroic, slay the dragon and rescue the princess. And shy guys know all about the dragon that is loneliness. They have fought it for years.
Not something I'd ever recommend for grabbing an extrovert, of course.