Hopefully, the number 5 is again a lucky number for the 2015 Steelers

It's ironic that the number 5 has become a lucky number of sorts for the Steelers.

That was the number of titles that eluded the team for over a quarter century as the slogan "One for the Thumb" hung over the franchise like a hangman's noose.

But today, as we are embarking on the start of the 2015 season, it's impossible not to notice how the No. 5 has become not a curse but a beacon of good things for the franchise. Dating back to 1975, the Steelers have played in three of the last four Super Bowls to end in the number 5, and on two of those occasions flew back to the Steel City with a Vince Lombardi Trophy in tow.

Many, including Steelers.com's Bob Labriola, feel that the '75 team is the best Steelers team of all-time. In 2006, NFL Network named that team as the seventh best team since the Super Bowl's creation at the conclusion of the 1966 season, with the '78 Steelers ranking No. 3 behind the '85 Bears and the undefeated '72 Dolphins.

Fresh off of winning Super Bowl IX, the Steelers blew out San Diego in Week One before being run roughshod by O.J. Simpson in a Week 2 loss at home. Needless to say, the Steelers responded with gusto, winning 11 straight following the loss that included season sweeps against Oilers and Bengals teams that went 21-3 against the rest of the NFL that season. In the playoffs, the Steelers eased past the AFC East champion Colts on their way to a AFC title game rematch with the AFC West champion Raiders.

Facing a team that would win next year's Super Bowl after climaxing a 15-1 season (including playoffs), Pittsburgh edged Oakland in one of the most physical games every played. Two weeks later, the Steelers upended the Cowboys in the most exciting Super Bowl at that time, 21-17. Lynn Swann stole the show, pulling in four passes for 161 yards that included the game-winning, 64-yard touchdown pass from Terry Bradshaw, who was knocked out of the game with a concussion shortly after throwing the winning pass.

Not to be out-shined was the Steelers defense, who saw a slew of players turn in career performances. Mel Blount recorded his second Super Bowl interception, while Mike Wagner's fourth quarter pick helped give the Steelers a 15-10 lead. Dwight White and L.C. Greenwood combined for six of the team's seven sacks of Roger Staubach, while Jack Lambert paced all defensive players with 14 tackles, 15 if you include his throw down of Cowboys safety Cliff Harris after the safety openly taunted Steelers kicker Roy Gerela.

Two decades later, the 1995 Steelers looked to be the team that finally won the franchise's elusive fifth ring. After all, this was a team that finished three yards shy of advancing to Super Bowl XXIX, and with seemingly everyone back save Barry Foster, the Steelers were the overwhelming preseason favorites to represent the AFC in Super Bowl XXX.

Unfortunately for the Steelers, their paper AFC championship didn't resonate on the field in the first seven games. The team staggered to a 3-4 start that included injuries to quarterback Neil O'Donnell and Hall of Fame cornerback Rod Woodson, who was lost for the regular season after tearing his ACL in Week One. But with Greg Lloyd turning in one of his finest seasons, Carnell Lake selflessly switching from safety to corner to fill Woodson's void, and the emergence of several young defensive players that included Levon Kirkland, Chad Brown, Darren Perry and Willie Williams, Pittsburgh's defense was again the most feared unit in football.On offense, Bill Cowher and offensive coordinator Ron Erhardt opened things up by employing a five wide receiver set that featured 1995 Pro Bowler Yancy Thigpen. They also unleashed "Slash", quarterback/wide receiver/running back Kordell Stewart, a rookie that played a pivotal role in the team's second half surge.

By season's end, the '95 Steelers had won eight out of their last nine games to finish 11-5 and earning the second seed in the AFC playoffs. And after defeating the Bills 40-21 and with the Colts shocking win over the No.1 seeded Chiefs 10-7 in the Divisional round, the Steelers would be hosting the AFC title game for the second straight year. In one of the greatest championship games ever, the Steelers prevailed 20-16 but not after withstanding Jim Harbaugh's Hair Mary pass that fell incomplete in the end zone on the game's final play. And while they fought valiantly against the 11 point favorite Cowboys two weeks later in Super Bowl XXX, they couldn't overcome two major second half miscues, meaning that the Steelers would have to wait longer to finally enjoy that fifth championship.

That title would not elude the grasp of the 2005 Steelers, who, like the '95 team, looked to avenge a painful loss an AFC title game that occurred the previous season. You could say that the Steelers run to Super Bowl XL began while the Patriots' 41-27 win in the '04 AFC title game was still winding down. It was then when rookie Ben Roethlisberger told potential soon to be retiree Jerome Beitts that if he returned for a 13th season, he would be rewarded with a Super Bowl championship.

Bettis did return, but after a midseason swoon had the Steelers at 7-5 and on the outside of the AFC playoff hunt, it appeared that Big Ben's promise might go unfulfilled. That's when Bettis took matters into his own hands, rushing for over 100 yards for the final time in a must-win over the Bears. The win ignited a four-game winning streak to close out the season, earning the Steelers the final seed in the AFC playoffs.From there, the Steelers became the first time in NFL history to win three playoff road games in the same postseason, culminating in a 34-19 win over the Broncos in the AFC title game.

In Super Bowl XL, the Steelers overcame a slow start to prevail over Seattle, 21-10. Just as Swann had done three decades earlier, Hines Ward stole the show, catching five passes for 123 yards that included the game-clinching touchdown pass to earn MVP honors. The defense was also at its best, as Casey Hampton's sack and Ike Taylor's interception late helped seal the victory. Big Ben's promise had been fulfilled, and Bettis' and the Steelers' long quest for the Steelers fifth Lombardi Trophy was finally put to rest.

This summer, we're again midway through another decade, a decade that again has seen the Steelers climb to near the top of the NFL. Pittsburgh already has won Super Bowl appearance in tow this decade, and after a resurgent 2014 regular season ended in bitter disappointment in the Wild Card playoff round, the Steelers will again be hungry to make history in a year that ends with a number that has been a good luck charm for this charmed franchise.