If by competent diplomacy you mean kowtowing to the Russian demands made on NATO, then perhaps. Your reliance on selective quoting from a biased, far-left website like Common Dreams is kinda funny, given your other viewpoints. And the selective quoting is par for the course for you and your ilk, never quite giving the full picture. If you click the NATO link, you get the full context. In relevant part, Stoltenberg said:
"Then lastly on Sweden. First of all, it is historic that now Finland is member of the Alliance. And we have to remember the background. The background was that President Putin declared in the autumn of 2021, and actually sent a draft treaty that they wanted NATO to sign, to promise no more NATO enlargement. That was what he sent us. And was a pre-condition for not invade Ukraine. Of course we didn't sign that.
The opposite happened. He wanted us to sign that promise, never to enlarge NATO. He wanted us to remove our military infrastructure in all Allies that have joined NATO since 1997, meaning half of NATO, all the Central and Eastern Europe, we should remove NATO from that part of our Alliance, introducing some kind of B, or second class membership. We rejected that.
So he went to war to prevent NATO, more NATO, close to his borders. He has got the exact opposite. He has got more NATO presence in eastern part of the Alliance and he has also seen that Finland has already joined the Alliance and Sweden will soon be a full member."
Putin's demands, which were more much more than no more NATO expansion, were a joke, and he knew NATO would never agree to them. When Finland joined, Putin basically shrugged his shoulders and said "Meh, no biggie." That should tell you all you need to know. It was never really about NATO expansion. Russia's policy since the late 1990s has been to reject the finality of the post-Cold War European order and the sovereignty or territorial integrity of the states that gained their freedom due to the end of the Cold War. But sure, it's all our fault.