Beginning in this weekend, the PBR will debut the official Power Rankings.

Based on a formula developed by PBR statistician Slade Long, the Power Rankings take into account round wins, riding percentages, high scores and success versus top bulls, measuring the efficiency of the top riders within a five-week period of time.

Based on the past five Built Ford Tough Series events, the Top 5 riders in the current Power Rankings are Robson Palermo, 94.91; Luke Snyder, 90.1; LJ Jenkins, 86.84; Fabiano Vieira, 86.71; and Guilherme Marchi, 84.72.

Only Palermo and Jenkins are ranked in the Top 5 of the world standings.

Valdiron de Oliveira, who has been atop the world standings for all but one week this season, is 23rd in the current Power Rankings.

The world leader finished in the Top 10 in 11 of the first 15 events, but made it back to the Built Ford Tough Championship Round only once in the past four events.

His riding average was once approaching 80 percent. However, during the timeframe reflected by this week’s Power Rankings, he covered only four of 11 bulls, and his current season average is at 66.7 percent.

On the flipside of the Power Rankings, Snyder and Vieira might come as a surprise.

After barely avoiding the cut twice earlier this year, the 28-year-old Snyder has recorded four Top 10 finishes in the past five BFTS events, including a much-heralded win at the Last Cowboy Standing in Las Vegas.

Vieira, currently ranked 17th in the world standings, has ridden his way into the Top 20 in just 12 of 19 events. Only once in that time has he gone 0-for-the-weekend. He nearly won the event in Des Moines, Iowa, finishing second to two-time World Champion Chris Shivers.

Leader board: In 11 of 17 regularly formatted BFTS events this year, the leader heading into the championship round has gone on to win the event. The six riders who haven’t held their leads include Ben Jones (at Sacramento, Calif.), Skeeter Kingsolver (Anaheim, Calif.), Aaron Roy (Oklahoma City), Jenkins (Chicago), Shivers (Glendale, Ariz.) and Marchi (Pueblo, Colo.).

Jenkins is the only rider who has led an event from start to finish, and he has done it twice. He led after the first four rounds in Albuquerque, N.M., finishing first in Round 1 and Round 3, and won the event despite not covering in the championship round. Jenkins also led from wire-to-wire in Seattle, winning Round 1 and the first short round, while tying for first with Robson Palermo in the championship round.

Event winners: There are 12 riders who account for the first 19 event wins of the 2011 season, and only four of them have won multiple events: Palermo, 4; Oliveira, 3; Marchi, 2; and Jenkins, 2. Palermo’s four wins ties him for seventh with 12 other riders on the all-time list for most BFTS wins in a single season. Justin McBride holds the record with eight wins in 2007.

Oliveira is the only rider this year to have won back-to-back BFTS events. He accomplished the feat by winning in Glendale and again in Fresno, Calif. The record for consecutive wins is held by Shivers, who won three in a row in 2000. There have been back-to-back winners in all but two seasons in the past 15 years (2002 and 2009).

Nine of the Top 20 leaders on the list of all-time career wins are still active bull riders, and only six – Shivers, Marchi, J. B. Mauney, Mike Lee, Kody Lostroh and Palermo – will be in Thackerville. Wiley Petersen, Renato Nunes and Travis Briscoe are not in the draw this week. Petersen is scheduled to return from injury next week in Billings, Mont.

Familiar state: This is the first BFTS visit to Thackerville, but the 30th stop all-time in Oklahoma. The PBR will be at the BOK Center in Tulsa on Aug. 12-13 for the Express Classic presented by American Hoggers on A&E. It will be the seventh straight year in Tulsa. Guthrie hosted 12 events from 1996-2004, including two stops in 1996-98, and Oklahoma City has hosted the BFTS 11 times. California has hosted the most BFTS events with 41, while Texas is second with 32. Oklahoma is third.

Back outdoors: This is the first BFTS event held outdoors since 2005 at the Laughlin Fairgrounds in Laughlin, Nev. Cody Whitney finished first there, and Lostroh finished second. There was also an outdoor BFTS event in Pueblo, Colo., in 2005.

Live Event Center: Follow all the action from this week’s BFTS event by logging on to the Event Center at www.pbr.com/live. The multimedia center provides in-arena audio, live scoring, live blogging and event-related interviews.

— by Keith Ryan Cartwright and Jack “Whiplash” Carnefix