I genuinely think part of the reasoning why we haven't gone for a back up striker or even a first choice striker is because the club knows that we could always put Cunha or Mbuemo in that position. In fact, now that Rashford is back, he could even go there. In the club's mind, we probably have enough cover for that position.
The part that doesn't sit right with me is that none of those players are fully committed to the cf position. The best fit is Sesko, and he is still learning his trade. The options for that position are very unconvincing.
At the same time, we are living in a time where the centre forward role has changed a lot and lots of teams tend to favour advanced midfielders, false 9 positions, or players out wide who drift inside. As well as that, there's a dearth of quality strikers out there, and even less who are available for transfer, and that's without getting into the cost.
What we're basically after is a substitute striker who can come into games late on and get us a goal from something out of nothing, like Hernandez used to do.