The more you budget for medical the better it works. Simply place a player on the 60 day DL (no matter how minor the injury) and leave him there till he gets 2 free 'bumps' in the ratings he took a hit in getting injured. Once two 'updates' occur, you might as well remove the player from the DL, as the bug won't help any more after that.

How many cycles does it take for the 2nd bump

Does it have to be 20 medical or can it work for 15, 10, etc

I think those medical bumps happen at the same time as the rest of the ratings updates.  It obviously works the best with 20 med, but I think it still works to a lesser degree with lesser budgeted to med.

And, you may or may not actually get any bumps from the player at all.

Sometimes they just sit on the 6-day DL, full healthy, without any recovery or improvement, even at $20M.

There may be something to being able to predict recovery based on the type of injury, but I haven't tracked it closely enough to know for sure.

Elbow injuries are great for pitchers, back injuries are good for power hitters, leg injuries are good for players who need range.

Some examples:

Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Ray Todd
Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: William Patterson
Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Jose Hernandez  He'll get another and improve in almost every pitching category
Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Arthur Dickerson

For the most part, the categories that improve are the ones that declined in the first place, and the exceptions usually make sense as described by Mike above.  I think that some of those "exceptions" are losses of less than a full point, but that's just a guess.

$20M is not a prerequisite, it just makes it more likely, and probably more often. I keep $18M and get it.

Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Raul Nunez is the latest.

I have gotten a small medical bug bump, usually only a point or two but rarely more, running as low as $14M medical.

Does this work if you have $15m in the medical budget, the guy is only injured for 7 days and you put him on the 15 day dl? Is there any benefit to putting the guy on the 15 day dl when he only needs 7 days to recover?

What do you guys do when a young player has an injury?

I just had a 19 year old prospect hit the DL with a 12 day injury - is is better to put him on the 7 day DL and then take normal development, or put him on the 60 day and take advantage of the injury bug?

7 day

You might get the medical bug bump, but you would be costing yourself normal development bumps in doing so.