Moeee,

The way the ratings work is purely based on times (with some track and box bias). Obviously each race time is going to be different for different reasons.
Thus the different ratings look at different time frames for the race times. The first rating (2 races) takes a look at a shorter number of races thus I class this as the current form of the dog. Whichever dog shows the lowest odds using this is more than likely the dog in "form". The 3 race rating is the one most people use as it allows a better feel for the last month of racing in the dogs career.
The 5 race rating (if available) is used for the medium term - longer term rating that shows which dogs have performed over their career. Further back than 5 races isn't really necessary but I sometimes do it if a dog has raced a lot.

The ratings allow me to look at which dogs have improved over the 5 race period and also which dogs just ran into a bit of bad luck. I usually look for a certainity which is a og which rates lower than $1.20 on all 3 ratings and then I check out the form. The form usually shows a couple of the other dogs got checked heavily. For instance you said Pedro Allen, Did you know in its last 8 starts it had been checked 6 times. This is because it was a bit slow out of the box, or because it had bad box draws. It lost a combined 22 lengths due to the checks. This shows that if this dog actually got a clear run he was a good chance. On the other hand our favourite Wannadoo had only been checked 4 of his last 8 starts and hadn't been checked at all in his 3 previous starts. This is because he usually gets away quickly but looking at his draws he has been running out of the inside boxes recently and this could have been improving his chances. Looking at Wannadoo also shows that he has not raced well in outside boxes with no wins from boxes 6,7,8.

So based on the form it looks like Wannadoo is not such a good selection after all. In fact it is about even with Pedro Allen if Pedro Allen can get a clear run. Of course in box 4 I wouldn't think this likely. o lets go to the speed charts. Looking at those Pedro Allen has the best split time marginally. And Box 5 is scratched which will give Pedro Allen an easier run. looking at his rating he had a Quick escape from the box last race and there is a good chance he could repeat this performance.

Looking further into this I noticed the dog in box 2 has been running wide which could be a problem for Pedro Allen. He has a 1 dog gap and this may be enough to get clear before any collisions occur. This also shows me the dog in Box 1 is going to get a nice clean run through the first corner. So my rating for Dog 1 should be up a bit more as he should get a good run and miht be able to rail it and get to the lead.

Finally the dog who ran third has a great record from box 8. He likes to run from the outisde boxes so he needs a rating boost as well.

I could through this for most of the dogs but it takes a long time to rate a race properly. That is why i use my 3 rating system to come up with some selections and then I concentrate on these races.

I hope this explains how I do some of my form and might help you in some of your ratings.

Good Luck.