Newcastle won 2-0 at St James' Park with Dan Burn and Joelinton scoring for the hosts.
Afterwards, Valverde lamented: “The result is a shame. They’re a very strong team physically, always press very high. That’s how the first goal came about.
"We had chances to equalise. The second goal hurt us, left us down for a few minutes. We reactivated with the substitutions. A two-goal margin is a shame because we put more than that into the game.”
On his substitutes, Valverde also said: "They reactivated us. Nico Serrano had chances, Selton Sánchez got into the game and Asier Hierro moved well.
"We’re Athletic Club and know we need to keep giving chances to these players who are good. The future of the club depends on them. If they got on it’s because they worked for it and are good. They showed they’re capable of it."