Catch, 3Fingered gave you a good start. According to DIII baseball, there are about 20 or so DIII players drafted each year. Can vary up and down, but not very much. So, 20 out of about 1,500 come from the DIII ranks. I don't think there is any information about those that are signed but not drafted. One major reason is that number does not just include free agents from the 50 states, the number includes players from the rest of the world. The latter is becoming substantial, more than most realize...until you go to a Milb camp for Spring Training.
If you go on MiLB.com each league list all transactions (including FA signings) each month. It would take some time checking each league but its a start
You go into stats,it shows leagues and there will be "league transactions" listed you click on it and you can check month by month
I don't know if I would count FA into the general scheme of things. FA are signed for many different reasons and many signed are those that are coming from other organizations (once drafted but released) as well as those (many seniors) that slipped through the draft and FA signings can occur at any time including during spring training.
I think that the Alvarez situation is causing MLB and the union to rethink the slot rules and enforcement. But I don't think anything will change until the current CBA expires in a few years.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .