HENDERSON, Nev. -- The Las Vegas Raiders are signing quarterback Desmond Ridder, a former third-round draft pick, off the Arizona Cardinals practice squad, a source confirmed to ESPN on Monday. Ridder, who has an 8-9 record in 19 career games with the Atlanta Falcons, joins the Raiders after starter Aidan O'Connell broke the thumb on his right (passing) hand in the first quarter of Sunday's loss at the Los Angeles Rams. O'Connell had replaced a benched Gardner Minshew last week but is expected to miss four to six weeks, a source told ESPN NFL Insider Adam Schefter. Minshew, after throwing three interceptions and losing a fumble that was returned for a touchdown against the Rams, is tied for the league lead with 10 turnovers, along with Tennessee Titans quarterback Will Levis. The Raiders also have undrafted rookie quarterback Carter Bradley on the practice squad. Ridder, 25, has passed for 3,544...