Are some batches of yeast just duds?

For my previous batch of weissbier I pitched Wyeast 3068 from a starter.  I was all set for a huge krausen like I’d gotten in the past with this yeast.  It was a little slow to start, but fermented steadily to completion and made a good beer.  I saved the dregs in a couple of quart jars.

I brewed another batch this past Friday.  I pulled the yeast slurry out of the fridge during the mash so I would warm up by pitching time.  I had about 10 oz of slurry and added a little of the wort from the chiller to stir it up, then pitched about 10 minutes later after finishing the chill and oxygenating.    Had another slow start-up and the beer’s fermenting like the previous one did.

Seems weird and wondering if I got a batch of lazy yeast.

Maybe, but I’ve hardly ever seen it happen.  Maybe something in your process of making a starter?  Dunno, just a WAG.  Also, I’ve read that letting the yeast warm up before p[itching means that it starts consuming it’s nutrients before it gets into the wort, which is not a good situation.  For the last 15 years and several hundred batches I simply take it out of the fridge and pitch immediately.  Works great.

Plenty of things can make the yeast less viable, which is why I always recommend starters for liquid yeast use (among other reasons). It could be old (check the date). It could have been left in the too-cold part ofd the fridge, or kept too warm for some time. A starter will mitigate these issues.