One reason: It couldn't get much worse than last year.
West Virginia returns most starters from the unit that was one of the most porous nationally in defending the pass and points allowed.
"By no stretch are we where we want to be," said Patterson, who began retooling the defense in January. "But thank God we're not where we used to be."
West Virginia was among three defenses in the Bowl Subdivision to allow more than 4,000 passing yards in the 2012 season. The 38 touchdown passes allowed were surpassed only by Colorado's 39, and only three other teams gave up more points than West Virginia's school-record 495.
The Mountaineers especially couldn't stop offenses on third down. Wide receivers were getting into the open field and West Virginia's defensive backs often were unable to track them down. While four losses were blowouts, there was a last-second defeat to Oklahoma and an overtime setback to TCU, both at home.
Patterson took over for Joe DeForest prior to last year's Pinstripe Bowl loss. DeForest spent one year unsuccessfully transforming the Mountaineers to a 3-4 formation from the 3-3-5 that helped the Mountaineers go 3-0 in BCS bowl games. DeForest is the special teams coordinator this season.
Patterson continues to coach linebackers as well. Tony Gibson, who coached defensive backs at WVU from 2001 to 2007, was hired to replace DeForest as safeties coach, while Brian Mitchell replaced the fired Daron Roberts as cornerbacks coach.
The Mountaineers are coming off a disappointing 7-6 season and have to replace quarterback Geno Smith and several other offensive stars, raising the likelihood the defense this year won't be taking the field as often trying to protect a lead.
While adding much-needed reinforcements, Patterson wants the defense to be more prepared for the furious pace of spread offenses in the Big 12. And the Mountaineers have only a month to get ready for the Big 12 opener at Oklahoma on Sept. 7 after the Aug. 31 season debut with William & Mary.
"The guys have heard me say it before: 70 percent of all big plays in Division I college football come because of misalignment or busted assignment," Patterson said. "Our whole philosophy is the faster we take the field, the more knowledge we can obtain from the sidelines."
The veteran players have differing opinions about whether to forget what happened or learn from what went wrong in 2012.
"Last year it was dreadful," said West Virginia linebacker Isaiah Bruce. "It's definitely not forgotten, but I have moved on. We all have moved on."
What matters is that everyone on the defense needs to understand their roles better, Bruce said.
"We can't have too many people getting out of position or trying to do too much or trying to do somebody else's job," he said.
"Because on defense, we're reacting to what the offense does. So if you are out of position and they decide to go that way, that creates a touchdown. We just have to communicate and understand exactly what we have to do and just do our job and be more disciplined."
Safety Karl Joseph said 2012 "is done with" and won't use that as a reference point. He does admit this year's unit has a chip on its shoulder and plans to be more physical.
Joseph and Bruce will be among the focal points. They ranked one-two in total tackles as freshmen and combined for four of the team's 10 interceptions.
Safety Darwin Cook and linebacker Doug Rigg played key roles on the Mountaineers' Orange Bowl-winning team from 2011. They're joined by linebacker Jewone Snow, who returns after missing the final eight games last season with a shoulder injury. Snow started seven games as a freshman in 2011.
Patterson wants to 6-foot-7 senior lineman Will Clarke's height as a way to slow down offenses looking for a quick pass across the middle.
Clarke said as bad as the defense was, the good news is "a lot of us played together last year. It's easier to get back on the same page and take the new things that coach Patterson is bringing in with us."