Optimism reigns supreme with the Dallas Cowboys after beating division rivals New York and Washington by a combined 28 points in Weeks 1 and 2.

The offense has been one of the NFL's most dominant and the defense has done a good job preventing opposing offenses from keeping up. They haven't been perfect, but you'd be hard-pressed to find a team collectively playing better than the Cowboys right now.

Still, it's not all daisies and dandelions, as there are Cowboys players who have yet to play up to expectations.

With that in mind, it's time to take stock of the roster by highlighting a few players who have exceeded or fallen short of expectations thus far.

Stock up: Dak Prescott

Dallas Cowboys quarterback Dak Prescott (4) warms up before an NFL game between the Dallas Cowboys and the Washington Redskins on Sunday, September 15, 2019 at FedExField in Landover, Maryland. (Ashley Landis/The Dallas Morning News) (Ashley Landis / Staff Photographer)

Dak Prescott is playing the best ball of his career, going 51 of 62 (82.3% completion rate) for 674 yards (10.9 yards per attempt), seven touchdowns and just one interception. He leads the league in passing touchdowns (tied with Lamar Jackson and Patrick Mahomes), yards per pass attempt, net yards per pass attempt (10.57), adjusted net yards per attempt (12.08), sack percentage (1.59%) and QBR.

Although many are quick to point out the Cowboys' soft schedule to start the season, Prescott's MVP-level play is rooted in a combination of improved footwork/throwing mechanics and Kellen Moore's scheme.

Old bad habits have surfaced on occasion, but Prescott's lower-body throwing mechanics have been much more dependable, even in the face of pressure, leading to more consistent accuracy and velocity on his throws.

This has benefited him immensely on deep passes (20-plus air yards). In 2018, Prescott had a 38.6% adjusted completion rate (completions plus drops, divided by attempts) on deep throws. This season's sample size is small, but he has an 87.5% adjusted completion rate on deep passes to lead the NFL among quarterbacks with at least two deep targets, according to Pro Football Focus.

When you combine Prescott's newfound accuracy with a Moore-led offense, the result is one of the league's most efficient offenses.

Moore has done an outstanding job of leveraging Prescott's strengths with his play-calling and design. After Scott Linehan used play action on just 24.9% of Prescott's dropbacks in 2018, 43.1% of them this season have used some sort of play action -- an 18.2% increase from last year, according to PFF.

The benefits have been larger throwing windows further down the field, as Prescott is completing 92.6% of his passes while averaging 12.3 yards per attempt off of play action. He has profited off of play action to the tune of an 18.3% jump in completion rate and an improvement of 2.6 yards per attempt, according to PFF.

Moore has also increased the frequency of pre-snap movement, arming Prescott with more actionable information once the ball is snapped. This has made it easier for Prescott to identify coverages pre-snap, making him more aggressive post-snap.

Prescott is playing at such a high level right now that he's bound to regress a bit toward the mean. But his improvement is no mirage, and this marriage between quarterback and offensive coordinator has created a way for Prescott to continue to be effective.

Stock down: Jaylon Smith

This isn't to say Jaylon Smith has played poorly -- because he hasn't -- it just means he hasn't played up to the expectations that come with a five-year, $64 million deal. For that type of money, Dallas needs Smith to perform at a level similar to last year, when he was one of the best MIKE linebackers in football.

Smith still makes freaky plays on occasion, showing off his bone-rattling hit power and ability to carry receivers and tight ends down the seam (above clip).

But he has been a bit more inconsistent with run fits than in years prior, which has left open lanes for opposing running backs.

Smith has especially struggled to get off blocks through the first two weeks, inhibiting him from being as effective as he's been before.

It appears as though teams are taking a page out of the Rams and Colts' playbooks from last season, when both dominated Dallas on the ground by making a concerted effort to get their offensive linemen to the second level as quickly as possible. Smith needs to do a better job of outpacing the blocks with his speed in pursuit or shedding blocks with his hands and explosive power.

Furthermore, Smith has been a bit more inconsistent as a tackler. Not only did he miss two tackles against the Giants, but a bad pursuit angle led to a Redskins touchdown last week (above clip).

Stock up: La'el Collins

The most improved Cowboys player through two weeks is undoubtedly right tackle La'el Collins.

Here are #Cowboys RT La'el Collins' best blocks against NYG.



Bodies were flying everywhere. Collins did a great job manipulating and exploiting opposing defenders' balance, particularly with the snatch & trap. Also doesn't hurt that Collins carries serious power in his hands. pic.twitter.com/65Ly0y06Iq — John Owning (@JohnOwning) September 11, 2019

After putting together a dominant performance against New York, Collins followed up by largely shutting down Washington pass rusher Ryan Kerrigan, who consistently got the better of Collins in their previous battles. That wasn't the case Sunday.

Collins' technique isn't perfect, but it's cleaner and more consistent than it has been at any other point in his career, which is a large reason he has been more effective in pass protection and run blocking.

La'el Collins personally created a running lane for Zeke. Caves in the DT on his double team then shields the LB at the 2nd level. 8-yard gain. pic.twitter.com/KMlEVPRwGu — John Owning (@JohnOwning) September 16, 2019

Collins leverages his power to land thunderous strikes that knock pass rushers off their line to the quarterback and caves defenders with down blocks on double-teams before climbing to the second level (above clip).

Can't blame him for rushing it, but wish Dak took his time to quickly set his feet and fire here. Very tough catch, but Cobb has to bail out his QB here.



Also, look at La'el Collins' recovery after being put off-balance by Kerrigan. I don't think that happens in previous years. pic.twitter.com/3gd741JjH2 — John Owning (@JohnOwning) September 16, 2019

Most notably, he has improved in his ability to recover when out of position. This has allowed Collins to sustain blocks long while preventing the quick pressures that occasionally happened in previous years.

While it was easy to discount Collins' dominance in Week 1 because of the level of competition -- the Giants may have the worst group of edge rushers in the league -- the same excuse cannot be made about his impressive performance opposite Kerrigan, a former Pro Bowler coming off three straight seasons of 10-plus sacks.

All in all, Collins, like Prescott, is playing the best football of his career. You'd be hard-pressed to find an offensive tackle in the NFL playing better than Collins is right now, including Tyron Smith (not to say Collins is better than Smith; he's playing better than Smith right now, which is different).

If Collins keeps this up, his five-year, $50 million extension will soon look like a huge bargain for the Cowboys.

Stock down: Anthony Brown

It's been a rough start to the season for Anthony Brown, who's been a bit inconsistent as a tackler and in coverage.

In the past, Brown was one of the most reliable tacklers in the secondary, but that hasn't been the case this season. After missing eight tackles total in 2018, Brown has already missed four in 2019. He has done a poor job of coming to balance before attempting tackles, allowing ball carriers to easily elude him.

Furthermore, Brown hasn't been as consistent in coverage as he was last season. In Week 1, Brown mostly played outside with Byron Jones on a pitch count, and he wasn't great. Brown had trouble giving up separation at the top of routes and often gave receivers too much space to work with.

With Jones back in his starting role Week 2, Brown was able to revert back to his best position -- the slot -- but still struggled, as Washington's slot receiver was able to shake free of Brown on short-to-intermediate routes (notably for two first downs) when the two were matched up.

While Brown has been able to stave off competition for the primary slot cornerback job in the past, his struggles -- combined with Jourdan Lewis' effective play through two weeks -- could lead to a change this season if he doesn't improve quickly.

Stock up: Travis Frederick

Travis Frederick's value to the offense cannot be understated.

The Cowboys' offensive line struggled mightily last season in Frederick's absence as the All-Pro's battle with Guillain-Barre syndrome sidelined him for the entire year. Although the offensive line was considered a strength, it actually became a huge weakness in Frederick's absence, finishing 22nd in pass-blocking efficiency (which measures pressure allowed on a per-snap basis with weighting toward sacks allowed) while allowing 169 pressures on 612 dropbacks, according to PFF.

The sample size is small, but through two games with Frederick back this season, the Cowboys' offensive line ranks first in pass-blocking efficiency, allowing just six pressures on 65 dropbacks.

Individually, Frederick still hasn't quite reached his pre-illness level of play. His balance and footwork remain a work in progress, hindering his ability to effectively climb and block at the second level.

Still, Frederick's presence and intelligence have been huge in terms of the offense getting into the proper protections and blocking schemes. Without Frederick in 2018, Prescott had a clean pocket on just 63% of his dropbacks (29th among quarterbacks, according to PFF). In 2019, Prescott leads the NFL in clean pocket percentage, seeing one on 84.6% of his dropbacks.

It's not a coincidence that the offensive line is a dominant unit with Frederick in the lineup and an also-ran without him.

Enjoy this post? More film studies:

-- 3 things we learned from Cowboys-Redskins, including what Kellen Moore is taking advantage of

-- Inside Dak Prescott's Week 1 performance, from all the good to the (very) little bad

-- Breaking down a clever wrinkle that helped Cowboys' defense keep Giants in check

Twitter: @JohnOwning