MLB Mercy Rule

I guarantee, I will not be the only one to blog about this, but the Texas Rangers beat the Baltimore Orioles 30-3. Isn't there a mercy rule in MLB? There is in Little League Baseball. And if there is not, shouldn't there be? Seriously.

Now, I will admit that my interest in baseball is passing at best, and I really don't understand ALL the statistics and data.. ERA for example.

As it was explained to me (and it could be wrong), they extrapolate how many runs a pitcher gave up for the amount of innings they pitched to determine what that pitcher would have given up, should he pitced an entire 9 inning game -- for example, a pitcher pitches 1 complete inning, and gives up 1 run. His ERA would be 9 -- assumes he would give up 1 run per inning (I'm sure I will be corrected if I'm wrong). So for an Orioles pitcher who gave up 10 runs, and pitched say... 1 inning (or worse... part of an inning). To give up 10 runs in 1 inning, would (according to my calculations) equal an ERA of 90... I think an average ERA is 3~5... but and ERA of 90? not good!