He will be sidelined until November as a result of an ankle injury he sustained during the match against Manchester City last weekend.
“When it rains, it definitely pours,” said Frank to reporters.
“They are unlucky injuries; they are not because we have trained players too hard or we haven’t made them strong enough.
“Of the eight players out, probably five would be starting - depending on the opponent.
“But it is what it is, and we need to deal with it. It’s a big part of a head coach’s job to find those solutions and make the team as competitive as possible.”
Frank continued: “Every time a key player goes out and another comes in, it makes the team a little bit different; no two players are the same.
“Both Kevin and Wissa are good at running in behind; Kevin is obviously quicker.
“Both are good in the air; I think Kevin is a little bit better. Wissa probably links the game a bit better; Kevin is a better pressing player. So there are different pros and cons.”