Carson Wentz vs. Earl Thomas: A heavyweight showdown | Jeff McLane

When Pete Carroll said last year that Carson Wentz would become a great player  – "There is no question," the Seahawks coach insisted – he wasn't inflating an upcoming opponent. The Eagles had already played and lost to Seattle.

Wentz tossed two interceptions, completed only 51 percent of his passes, and averaged a paltry 4.8 yards per attempt in the 26-15 defeat. But the numbers hardly told the story of the rookie quarterback's first foray into CenturyLink Field and against the Seahawks' Legion of Boom defense.

"He was poised," Seattle all-pro cornerback Richard Sherman said then. "He wasn't shook. He's a rook."

Wentz is no longer a rookie, and Carroll's and Sherman's words have proven prophetic. Two of the best at their craft noticed something special in the quarterback, despite his faults that day. A year later, Wentz returns to the great Northwest with arguably the NFL's best team and as a legitimate MVP candidate.

"He's really comfortable with the challenge of it all. It's not too big for him," Carroll said Wednesday on the eve of the Eagles-Seahawks rematch. "You can sense that in his play and when you're on the field with him, regardless of what that game meant. … He has all the elements to be a great player."

If Carroll's recent comments seem less enthusiastic, it could be the daunting challenge he faces without half of his famed secondary. Sherman and strong safety Kam Chancellor are out for the season. But free safety Earl Thomas, perhaps the most important piece of the Legion of Boom, will likely be in center field watching Wentz's every move.

Thomas missed practice Thursday with a heel injury, but he returned Friday and is listed as questionable for Sunday night.

If there's a matchup to watch within the game, it's Wentz vs. Thomas – the NFL's future at quarterback against the league's best defensive quarterback. They may not even come within 10 yards of each other, but Wentz's effectiveness will likely be tied to how he handles Thomas.

"Any time you have a safety like that who has free rein to be all over the field – that's big," Wentz said. "You kind of got to know where he's at all times, pick up some tendencies, which there aren't many. It seems like he has no real responsibility. It seems like the coaches tell him to make plays and fly around.

"You got to be smart with using your eyes."

Wentz has improved in all areas, but he has taken a leap in his ability to move defenders with his eyes and subtle movements. Last November, the Seahawks broke up several of his passes simply by reading his body. Chancellor scored an interception from underneath a route when Wentz stared down Dorial Green-Beckham.

There were other missed opportunities. Wentz took an early sack when he likely could have hit an open Nelson Agholor. And he tossed his second interception – this time to Sherman – when he threw deep to a double-covered Bryce Treggs.

"There's definitely a lot of plays we left out there last year," Wentz said. "They made a number of plays and we got down. We kind of shot ourselves in the foot."

Two first-half plays were silver bullets. A screen pass that Zach Ertz took 57 yards for a touchdown was nullified by an Agholor illegal-formation penalty. And a series later, Agholor bricked a downfield strike from Wentz.

Agholor, who has also progressed in one year, wasn't the only receiver to fail his quarterback. Green-Beckham and Jordan Matthews also dropped passes. Reverse those four miscues and Wentz's day might have looked much different.

He had several strong throws, the type now taken for granted because they happen with regularity. Wentz flicked a 19-yard pass to Brent Celek across his body as he stepped up in the pocket. He roped a 26-yard BB to Matthews. And he found Green-Beckham for a late touchdown.

"You could just tell right from the opening snap he wasn't going to flinch," Eagles offensive coordinator Frank Reich said last week. "He wasn't even the slightest bit intimidated."

The Eagles lost their next four games and Wentz's rookie season struggles continued. But there were more than enough glimmers of promise down the stretch and he has delivered upon them. Some of his Year 2 advancements have been natural. The skill-position upgrades, notably the addition of receiver Alshon Jeffery, have also helped.

Wentz and the favored Eagles are a confident bunch. The Seahawks, home underdogs for the first time in five years, may be without Sherman and Chancellor, but they have quarterback Russell Wilson, one of the best linebacker duos in Bobby Wagner and K.J. Wright, and Carroll's deceptively simple Cover 3 defense.

"It kind of cuts your playbook in half," Wentz said of the zone scheme.

Thomas can cut the field in half himself. Carroll, who is considered one of the best defensive back coaches in modern NFL history, knows a great safety when he sees one.

"You see great conviction out of him," the Seahawks coach said. "When he's something he knows what it is and feels the quarterback, he goes as well as anybody has ever done it."

Thomas left last year's meeting early in the third quarter with a hamstring injury. Wentz has been studying his tendencies on film all week. But the same could be said of the safety, who has allowed only 10 catches for 153 yards when targeted this season, according to Pro Football Focus.

Thomas can play up in the box, as well, but the post in his domain, just as it is for Eagles safety Rodney McLeod.

"It's literally a mind game between you and the quarterback," McLeod said.

Eagles rookie Tre Sullivan played the part of Thomas last week. The scout team typically goes less than 100 percent as to give each unit its "looks." But Eagles coach Doug Pederson altered the formula for Seahawks week.

"He told us to get after them," Sullivan said, "and turn it up more than usual."