It doesn't work that way. What if the 26 games were easier than the first 12 games? Performances don't always equate to results. I've seen us play well for 10 games and hardly amass any points and poorly for 10 games and get a nice haul of points. Last year is actually a prime example. We were very poor for a lot of the second half of last season and relied on the magic of one player to turn defeats into draws and draws into wins. In the case of last season our worst run of form came during a block of fixtures where we lost to Chelsea, City and Arsenal. If those exact fixtures occurred during the last 26 games of the season we would have still likely lost them and then the form doesn't look so good does it? Seasons are played from August to May.
Besides, every new season is a clean slate and what happened the season before has no bearing on the season to come. Anyone can take a point in a season to another point in the season approach and spin facts from it simply by taking a point of the season that suits your argument. Why 26 games? Why not look at the last 30 games? Do the 4 games before the 26 games not count? Why not just focus on the last 10 games of the season? We won 50% of those, W5 D3 L2 = 18pts or just over 68pts during a season. Or we could do the last 14 games and then our stats look far better.
The bottom line is judging form on results is over rated, because some games and some sequences of games, are clearly easier than others. If we have a 5 game stretch of playing City, Liverpool, Chelsea, Arsenal and Utd away and come out of that with good performances and 0pts the first guide for those 5 games makes us look like relegation candidates when we clearly would not be. Likewise we play the 5 weakest teams in a row at home and win them all we look like title contenders which in reality we would not be.