Expert opinion on betting strategy

Hello all

I am writing this post hoping I can find someone expert on sports betting in order to tell me that either I am wrong or lucky.

A few weeks ago I started a project in order to provid a betting strategy for soccer (final result market). In short, the algorithm checks the previous games (around the last 10 games) calculates the relative strength of a team (home away total) and then assigns a % to home draw and away result.

It then compares the % with the betting house odds: if draw % is 60 and draw% of betting house is 30% it assigns a ratio of 2.0.

Then it sugests a bet for ratios higher than a certain threshold.

So far so good. However this model (which is far from being calibrated) is giving returns of 80% (over 25 bets per year) and returns of 40% (over 100 bets per year). How do I know? I ve backtested the model for a few years across 22 leagues.

The data (historical results and odds) were gathered from

https://www.football-data.co.uk/downloadm.php

I can drop the excel and provide full details om metodh however is it possible to get such high returns? Are these strategies common? Are people making money using historical data?

Thanks for any help and will gladly comment on ay question. 

Best regards

LOL

Sorry. I didnt got your comment....thanks in advance for explaining it.