Delmas was drafted 33rd overall in the 2009 Draft, while Quin joined the Lions in the off-season from the Houston Texans.
Schwartz told reporters: "If we can keep that pair of safeties on the field, they can be as good as anybody in the NFL. Hard to mismatch us. We can match tight ends. We can matchup against wide receivers. Both guys can play in the box.
"Both guys are good in the deep part of the field. Both of them are good tacklers. Have good range. It's definitely an advantage for defense to have two safeties like that."
Detroit open their season on Sunday against the Minnesota Vikings.