There's a tiresome article on LabourList which can basically be summarised as: "Kezia Dugdale is a woman, so if you were critical of her leadership, you're a misogynist". It starts off with the following question, which is supposed to be rhetorical -
"She writes in her resignation letter that she leaves the party in a better state than she found it, and my goodness isn’t she right."
No, she's completely wrong, actually. Her electoral record is mixed, but it's undoubtedly more bad than good. Excluding the Brexit referendum, she fought three nationwide elections as Labour leader, and these were the results...
May 2016 Holyrood election: Labour suffered a net loss of 13 seats, slipping from 37 to 24. This was by far the party's worst performance since devolution in 1999, and the first time they had slipped to third place - both in terms of seats, and the popular vote on the list ballot.
May 2017 local elections: Labour dropped roughly 11% on the popular vote, finishing with just 20%. They lost 132 seats across Scotland, relinquished control of Glasgow City Council for the first time in decades, and slipped to third place nationwide behind the Tories.
June 2017 general election: Labour slumped to third place for the first time since 1918 in terms of seats, and for the first time since 1910 in terms of the popular vote. Paradoxically, however, they enjoyed a small gain of 2.8% in the popular vote, and jumped from one seat to seven.
Dugdale's claim to "success", therefore, rests almost exclusively on the seat gains in June. The recovery in the popular vote was pretty small beer, and only looked impressive in the context of the lowered expectations that the leader herself can be considered partly responsible for - Labour would initially have been expecting pretty much any successor to Jim Murphy to do a little bit better than 24%.
But even the seven seat haul looks considerably less thrilling when you bear in mind that the Lib Dems won 11 seats in 2010 with just 19% of the vote, and the SNP won six seats at the same election with 20% of the vote. Murphy was actually pretty unlucky to win just one seat with his 24% share - it only happened because the first-placed party was unusually dominant. The modest gains this year were thus a resumption of normal service for a party languishing in the 20s, not some kind of great leap forward.