ALAMEDA Jack Tatum Jersey , Calif. (AP) — Derek Carr knew there would be growing pains adjusting to a new offense for the Oakland Raiders under coach Jon Gruden.The surprising part for Carr and the Raiders is instead of showing steady progress throughout the year, the offense instead has regressed.The Raiders (1-8) head into Sunday’s game at Arizona (2-7) having gone back-to-back games without a touchdown for the first time since 2012, with the nine combined points in losses to San Francisco and the Chargers marking the lowest two-game output for Oakland since 2009.“It gets frustrating because I know how hard some of our guys work and you expect it to continue to go this way,” Carr said about the early season progress that hasn’t been maintained. “But this league, it’s tough man, and it’ll humble some guys really quick. … When you turn the film on it’s like, dang, if I just had that, or if I just would have checked to this or done this.“You can sit there and second-guess it all the time, but the only thing that we have the opportunity to do is do our best right when it’s in front of us. So, that’s what we have to do better, we all have to play better. Coach puts us in great positions, we just have to play better.”The Raiders will try to improve the production this week despite possibly missing several key pieces on offense. Receiver Martavis Bryant is out at least a couple of weeks with a knee injury and receiver Jordy Nelson didn’t practice Wednesday with a knee injury that has put his status in doubt this week.Oakland already is without injured running back Marshawn Lynch, who is on injured reserve with a groin injury, and traded away No. 1 receiver Amari Cooper last month to Dallas.That will likely give an opportunity this week to rookie Marcell Ateman, who began the year on the practice squad and has been inactive since getting promoted to the 53-man roster last month. Undrafted rookie Saeed Blacknall was promoted from the practice squad Wednesday and also could play a role.Carr has been impressed with Ateman’s hard work at practice and attention to detail.“One thing that really stuck out is during games, he’ll come up to me and ask questions, not in a bothersome way or anything like that just Marcus Allen Jersey , ‘Hey, what did you see here? What if they ran the route like this?'” Carr said.“So, I can tell that he’s not just here taking a redshirt year, enjoying his time wearing the team colors, he’s really put in a lot of work and it means something to him. He’s shown that, so hopefully he just goes out there and cuts it loose, because he’s done all the right things, now he’s just got to go play.”Ateman showed flashes in training camp, as he was able to use his size and jumping ability to make contested catches even when going up against the first team.Ateman said the past few months of practice have made him even more ready to perform on Sunday.“I didn’t take a back seat when I got on the practice squad,” he said. “I kept working that so when I get my opportunity I’m better.”NOTES: C Rodney Hudson (ankle), G Kelechi Osemele (knee), CB Gareon Conley (ankle), CB Daryl Worley (shoulder) and LB Kyle Wilber (knee) were all limited in practice. … The Raiders also signed WRs Rashard Davis and WR ArDarius Stewart to the practice squad. Isaiah Johnson, CB, Houston Measurables6’2", 205 pounds4.40 40-yqrd dash36.5-inch vertical leap133-inch broad jump6.81 second 3-cone4.06 second shuttleStats2018: 66 tackles, 5 passes..."Isaiah Johnson, CB Bo Jackson Jersey , Houston Measurables6’2”, 205 pounds4.40 40-yqrd dash36.5-inch vertical leap133-inch broad jump6.81 second 3-cone4.06 second shuttleStats2018: 66 tackles, 5 passes defensed, 2 INT2017: 45 tackles, 7 passes defensed, 2 INT2016: 15 catches, 165 yards (converted from wide receiver to cornerback after sophomore season)AwardsNoneStrengthsPaul Guenther looks for long, athletic corners with the ability to play press man coverage, and Johnson was one of the most athletic cornerbacks available in the 2019 NFL Draft. His natural athleticism allows for fluidity in his movements, and helps give him excellent change of direction skills. He also possesses elite speed (4.4 40).Possesses above average ball skills, and his speed and length allow him to both run with speedy receivers and offer great recovery speed. His experience on the offensive side of the ball as a former wide receiver at times seems to lend him the benefit of a better understanding of what the offense is doing. His size, strength and speed allow him to match up against more physically imposing receivers. Add in that he was also a special teams mainstay during his time at Houston, specifically as a gunner on the punt unit, where his length and speed regularly allowed him to both fight off and run away from jammers, and it’s easy to understand the upside the Raiders see in him.WeaknessesHaving spent his first three seasons at Houston as a wide receiver, and a defensive back the past two seasons, he is still learning how to play the position and his technique is still raw. As a result, he is sometimes susceptible to being embarrassed by more polished receivers Lester Hayes Jersey , such as was seen when he faced off with Deebo Samuel, a second round pick of the San Francisco 49ers, in a practice at the Senior Bowl. Further, while he is certainly a willing tackler, with just two years of experience on the defensive side of the ball, his form can be questionable at times. VerdictJohnson certainly possesses the athleticism and physical build to develop into the type of press corner that the Oakland Raiders are looking for. However, having only played on the defensive side of the ball for his junior and senior seasons, he remains extremely raw. The talent and physical skills are readily visible on tape, and with time and effort he has the potential to develop into a high level corner. That said, getting to that point will be a process, and not something fans should expect right out of the gate.Fit with RaidersThe first place he is likely to contribute is special teams, where willingness to participate on punt and kickoff coverage will be welcome. Beyond special teams he should provide depth in the secondary, as he has the length to step in on the outside if necessary and the athleticism to cover the slot if called upon to do so. As depth, he’ll be able to hone and further develop his skills as a defensive back without the pressure of being one of the team’s top two corners. That should give him the time he needs to further refine his game to the point where it is NFL ready. Also see: BD Williams’ Film breakdown: Trayvon Mulllen vs Isaiah Johnson reps