Burnwinter Merino is depth - which is what he was bought for anyway.
Havertz is fine as either a starter or main depth in a title chasing squad - as we saw last season when he was probably our best player from January to June. How we link the 8, 9 and left wing positions is what is key. We need more box bombing from the 8, and we need more internal runs from the 11. Martinell did this well yesterday, which he hasn't done all season - and it was particularly helpful because when we play with Merino or Trossard up top, we are very dependent on the wingers providing box presence because these guys (and Odegaard) all constantly go deep.
Someone complained that Odegaard didn't hit Martinelli on a run yesterday. Strikers go on runs all the time that nobody sees. But the other issue we have is Martinelli has not been making that run all year - so it's likely not something that Odegaard would've been scanning for. A lot success in this game comes from repetition and pattern recognition. So fix movement on the left as a priority.