He said, "Yes, that is one of the issues in constructing the squad, where we have to improve, to do things better to construct a squad where we have more depth.
"I think the most important thing is to return players and to get them back. In many positions we created depth and now in some positions we don't have choices.
"For instance, the left back position. (Luke) Shaw only 15 starts this season so far and (Tyrell) Malacia zero starts. Not even available."
Ten Hag also said: "Left back depends on availability from Luke Shaw.
"He is returning already on the pitch, we expect him back in coming weeks. But with Malacia it depends on his availability.
"I think every manager wants players with winning attitudes, great mentality, big personalities to perform under stress. That is what every manager is looking for. In this club, it is extremely important to perform under stress."
He added: "In the two (winter) windows, we didn't do almost no business.
"The first we loaned Wout Weghorst and Marcel Sabitzer, which were two good ones but in this winter we didn't do anything. We tried but it didn't happen.
"It had to do with the budget and FFP (financial fair play)."