The OIL Power Rating is based on the power rating created by the Oberon Mt. Fantasy Football League, which has been featured on ESPN's Fantasy Focus podcast and is used by many leagues across the country. From their website: 
The Formula

The Oberon Mt. Power Rating Formula attempts to give commissioners and owners alike a tool to predict a fantasy team's potential performance by not only looking at their average score, but also factoring in intangibles such as an owner's managerial skills (using winning percentage) and luck (good teams losing to the hot team of the week and poor teams beating better teams having a down week). 

Oberon Mt. Power Rating Formula

The Oberon Mt. Power Rating Formula combines Average Score (60%), Highest Score plus Lowest Score (20%), and Winning Percentage. (20%) to come up with a team's Power Rating for use in comparing teams both in the same league in ways other than just by Win-Loss Record. The Oberon Mt. Power Rating Formula is sure to provoke endless hours of trash-talkin' and one-upsmanship!

Besides comparing teams in the same league during the same season, our Power Rating is handy for comparing teams from previous seasons (same-sized leagues only). Simply plug the stats from the older team into the formula and you can get an idea who had the best team of all time in any particular league. A feature certain to spark hours of entertaining debate. (If there have been major scoring rule changes, simply treat them as different leagues - see Multi-League Protocols below)
The OIL's adjusted power rating takes everything measured by the Oberon Mt. Power Rating Formula and then calculates how each team compares to the rest of the league for that season. So, what is measured is not raw data that fluctuates by season but, instead, how much better or worse a team is than the average team for that season. But first, the baseline raw power rating needs to be calculated.

The Oberon Mt. Power Rating Formula is best explained by its creator: 
(avg score x 6) + [(high score + low score) x 2] +[ (winning % x 200) x 2]
​10
In English:
​
#1. Multiply the team's average score by six. Average score is the very basic stat to judge a team's prowess.

#2. Add the team's highest score to their lowest score (Deviation), and multiply the result by two. Over and above the average score, the Deviation gives more importance to a team's highest scoring game, while also punishing a team a little more for their lowest score.

#3. Take the owner's winning percentage and multiply by 200, then multiply that by two. This portion of the Formula more than anything rewards and punishes for all the little intangibles associated with coaching a fantasy team. For instance, an owner that continues to win despite a less-than-impressive lineup is rewarded over and above their lagging average score. On the other hand, an owner that loses because he starts players on their bye week, or leaves injured players in their lineup, suffers twice . . . from points not scored by missing players and for the resulting losses.

#4. divide the total by 10.

The result is the Power Rating . . . or, if you like, the Potential Rating, since it actually is meant to judge the potential score a team might be expected to score on any given weekend compared to its average score. Remember, as the season progresses, a team's average score changes more and more slowly as the number of games included increases. The Power Rating formula takes not only the average score into account, but also recent extreme high or low scores, and winning or losing trends. Obviously, you will need a few weeks of data before a viable PR can be arrived at. We don't start reporting Power Ratings until after Week 3 games.

Definition of Terms:

Average score - Total of a team's points scored divided by the number of games played.

Deviation - Take the team's highest score and add to it the team's lowest score.

Winning Percentage. - Divide the team's number of wins by the number of games played.
The OIL has taken the Oberon Mt. Power Rating Formula and added one wrinkle to better compare teams from different seasons. For example, a 2018 team might have the same record as a 2010 team but more points scored. On its face, the 2018 team is superior. But, if the league-wide scoring in 2018 is significantly more than it was in 2010, the 2010 team may have been more dominant. That is what we aim to discover using the adjusted OIL Power Rating. The formula for the adjusted OPR is: 
To determine the adjusted OPR for Team One (T1):

  1. First, calculate the raw OPR for each team; then
  2. Divide T1's raw OPR by the average of all teams' raw OPR.

This results in a number that is a multiple of the average power rating for that season. The absolute baseline score is 1.0, meaning that team's power rating is exactly the average power rating across the league. Anything below 1.0 is a below-average team; anything higher is above-average. What this provides is context, as it is difficult to compare a 2006 team to a 2018 team. The offenses have exploded, and every team is scoring more points and achieving higher power ratings on average just as a result of more fantasy points being scored in general. Over the course of an entire season, approximately every 0.045 points above or below 1.000 correlates to a win or loss

In action, it works like this:
In 2012, Lucky Enuf finished 6-7 and missed the playoffs. But was his team bad or just unlucky? His raw OPR was 172.07, while the average for 2012 was 155.32. Applying the adjusted OPR formula (172.07/155.32) shows that Lucky Enuf was 1.108 times better than the average 2012 team. An adjusted OPR of 1.108 indicates that Lucky Enuf was one of the stronger teams in the league that season but fell victim to a tough schedule (for comparison, the 2012 champion's adjusted OPR was just a tick higher at 1.133).

Similarly, in 2013, the DARC NARCS finished with a losing record and missed the playoffs. In 2015, they won 11 games and finished second in the NFC. But, compared to the average team of each respective season, the 2013 DARC NARCS  that finished 6-7 were a better team (1.116) than the 2015 version that went 11-5 (1.113). This was even while having a winning percentage 20+ points worse than they boasted in 2015 (winning percentage is weighted at 20% of the OPR raw score).
The OIL Record Book spreadsheet includes OPR for each manager, as well as a power rating for each of their seasons. You can view a manager's overall power rating and their top-rated and lowest-rated seasons on the main Manager Rankings spreadsheet. On each manager's spreadsheet, you can view the power rating for every season, the average power rating, and the top-rated and lowest-rated seasons. The "Overall" tab (below) has each manager sorted by career OPR.