I've been concerned about the same thing before, but I'm pretty sure it has no effect.

If that were the case, VL would improve at above half the rate as VR since you face around 65% RHP. 

DHs show improvement in their fielding ratings, even if they've never played in the field.

Thanks for the answers. Seems kind of silly that way, but it's good news because this makes it easier to avoid overusing players.

I've played scrubs ever since I lost my prized AAA SS prospect to a season ending injury. I never considered a development boost. Is the risk worth the reward? Obviously no one wants to lose a big prospect to a meaningless spring training game. However if the risk of injury is no greater than regular season and there is an opportunity to see a point or two in development, I may need to reconsider that approach.

I am in the play the scrubs corner. I'm too paranoid about ST injuries.

I'm not an expert, but the way I see it, there's a risk of an injury in any game, so the only way to completely avoid it would be to not play a guy at all. Obviously a prospect isn't going to develop if you do that. So my philosophy is just to have a high medical budget and not worry about injuries too much. Some prospects get 2, 3, even point bumps in ratings if they play in spring training. To me, the chance to get that bump is worth a small injury risk.

But if you don't have a prospect, go ahead and play the scrubs over your fully-developed Big League guys. Correct me if I'm wrong, but there's really no advantage to playing those guys in ST.

So what's the verdict? Assuming a good medical budget does the reward outweigh the risk of playing prospects to get a development boost?

As artic somewhat implied, are you going to rest them all year?   Play the prospects in ST and regular season.   Then, when they get fatigued, rest them.    You're far better off a player gets an injury in ST game 3 than RS game 141. 

What risk are we talking about?  They may get hurt at any time.  Does it matter if they get hurt in the regular season or spring training? What's the difference?

With prospects, the regular season games are no more meaningful than ST games, unless you really care about that AA World Series trophy. So no need to worry about a guy getting hurt in ST and missing out on all that hot minor league action. As Mike points out, your player will have a lot more time to recover from an injury in ST than late in the season. So go ahead and play the prospects.

If you're worried about injury risk (albeit a low one), It makes some sense to rest your fully developed Major League guys, though, since they eventually are going to play games that matter. Well, as much as anything in HBD can matter, that is.

To explain a little deeper say your prospect suffers a 33 day injury in ST.   You put him on the DL.   He gets two recovery bumps(how effective depends on your training budget).    He sits the first 50 games on the DL and is available to play the other 94.   If his DUR isn't fully developed, he probably wasn't going to play in that many more anyway. 

If he gets injured in game 133, he gets one recovery bump and likely accumulated less than 50 more AB than in the other scenario.