I've done a bit of testing, and the best I can get the ratings is an average 35 over score of 213 for 5. That's just over six runs an over, which I think is pretty fair considering 50 over games are normally around 250 and T20 games are normally around 150 (we're not talking roads here, just normal pitches that offer a bit for the bowlers). As those of you who've worked with cricksim before probably know, when you shorten the length of the game it's very hard to keep the wickets high as well as increasing the run rate, hence why five wickets is probably one or two less than an average real life innings.
Also all of the ratings are fixed, so all of the batsmen have the same batting rating and so on. Therefore because Tuffey is a pure bowler while Mills is a bowling AR, Tuffey's bowling is actually rated higher than Mills just to keep things simple, when in real life Mills is better than Tuffey.
Just to keep things moving I might post a couple of matches a day.