This time 2 years ago, the Tories looked well on track to win the next GE, and Labour looked to be crisis. What has happened since then (it appeared that the Owen Patterson scandal, even before Partygate, ignited things, has been seismic).
Ultimately Starmer has been a hugely successful leader of the opposition so far, as he when he took over the party had 202 seats in the commons (7 fewer than when Kinnock took over for perspective) and many people were saying that realistically all they could achieve at the next GE was making solid gains and reducing the deficit as much as possible. But now they look well on track to win a majority. Far more importantly, I hope he will a successful PM. I don't want the highlight to be the Tories being booted out the next GM, and to be underwhelmed after then.
Blair was both a successful leader of the opposition (Labour were already going to win a comfortable majority in 1997 without him, but he increased the size of the majority to 'super landslide proportions), and IMO was a very successful PM until he passionately supported the illegal invasion of Iraq.