Let's look at Josephs record as a defensive coach:
Houston Texans
Joseph joined the coaching staff of the Houston Texans in 2011. He served as the defensive backs coach under defensive coordinator Wade Phillips and head coach Gary Kubiak. Joseph helped the Texans to three consecutive top-seven NFL rankings in overall defense. Joseph’s secondary contributed to the team allowing the third-fewest passing yards per game (203.5) during that three-year stretch, helping Houston to its first two division titles in team history and playoff wins from 2011–12.
Cincinnati Bengals
Joseph was hired as the defensive backs coach of the Cincinnati Bengals in January 2014. Joseph helped the Bengals to back-to-back playoff appearances as their defensive backs coach from 2014–15 under head coach Marvin Lewis, guiding a unit that contributed to a league-best 41 interceptions during that span.
Miami Dolphins
Joseph was announced as the defensive coordinator of the Miami Dolphins for the 2016 season under head coach Adam Gase. Joseph oversaw a defense that played a key role in the Dolphins returning to the playoffs for the first time in eight seasons. Despite having to use 13 different starting lineups due to injury, Joseph’s defense ranked fourth in the NFL on third downs (36.2%) while forcing the sixth-most negative plays (107) in the league. The Dolphins won nine of their final 11 regular-season games in 2016 with Joseph’s defense accounting for the fourth-most takeaways (21) in the NFL during that stretch.
Denver Broncos
Joseph was hired as head coach for the Denver Broncos on January 11, 2017, after signing a four-year contract.
Joseph finished his first season (2017) as head coach with a 5–11 record and improved to only 6–10 in his second season (2018), resulting in back-to-back losing seasons for the Broncos for the first time since the 1971/1972 seasons. On December 31, 2018, Joseph was fired by the team. In terms of statistics, the Broncos' defense ranked in the top five in total yards, rushing yards and passing yards in 2017 and 2018. The defense ranked #13 in total defense in 2018 and #23 in 2017.
Somehow I don't think Joseph is the problem with the Cardinal secondary not being able to cover WRs. His history tells a different story. Sources were Wikipedia and Pro Football Reference.