Could someone help describe the rule 5 players for me.

Specifically does the team need to have those players in the minors for a set period of time after being acquired .... before they can be protected??

One poster mentioned that Avendano was acquired in the Rule 5, but we could lose him again in the next Rule 5 Draft.

Why wouldn't we protect a guy like him who's obviously having great success?

Pretty simple.

All players not on the the Major League 40 man roster who fall into the following criteria are eligible:

Players who were signed when they were 19 or older and have played in professional baseball for four years are eligible, as are players who were signed at 18 and have played for five years.

In simple terms almost all high schooler players and international signees from 2008 have to be added to the 40 man roster or be exposed to the rule 5 draft. Also all 2009 draftees from college (there are some examples of 19 year old high school kids but not often) will be exposed to the draft too. If a player is selected in the major league rule 5 draft the team must pay $50,000 and keep that player up on the major league 25 man roster all season or offer the player back to the original team for $25,000 and that player has to clear waivers through the league. Any team adding him through waivers must keep the player on their roster for the season as well though or once again the player will be returned.

In the case of Avendano, all players who were eligible but have not yet reached AAA are eligible for the minor league Rule 5 draft. There is still a cash settlement for this transaction but it's much smaller ($4K I believe) but there is no agreement in the minor league rule 5 about adding the player to the 40 man. However, the next season the player must be on the 40 man roster or be revealed again. The Jays might not have room for Avendano on the 40 man this off season so he might be revealed to the draft again.