In short, yes certain champs are always less viable depending on what's strong currently.
The Meta really determines which champs are in and which are out. Anything can shift the Meta, and often times you'll see a few shifts during each season. Hyper carries do well when there's a lot of champs with peel. So When there's a lot of tanks you'll often see hypercarries, as they need peel to do well. ADC's for this are vayne/jinx/MF. Tryn for the most part fits into this camp, he needs good peel in larger fights
If assassin's are in then you'll see a lot more champs with roots and single target stuns. as having two champs dive your team requires stopping otherwise they'll take out your squishies. Single target stuns usually have shorter CD's and so it gives you the ability to stun champs in succession. Adc's in this meta tend to be bursty so that they can protect themselves from squishy diver's like graves, corki, or ezreal. Tryn usually falls short in this meta from all the single target stuns or roots stopping him from reaching the adc in time to 2-3 shot them, and usually stopping him from escaping as well. This meta usually comes around when either tanks are less effective, or instant damage is just really high.
If poke becomes meta, you'll see a lot of squishier champs with high pushing potential, and low engage potential. This comp relies on slowing champs at long range, and not necessarily killing, but rather forcing champs out of lane, and fights, so that they can push towers. This comp comes riddled with a lot of long range slows and usually a good peeling support along with a champ with high pushing potential, like caitlyn/jinx/MF, and often has a lot of waveclearing champs as well. Tryn falls short in this category as a lot of the champs in this meta will nuke him hard before he even reache's the fight, and usually they kite very well with lots of slows so he has very little chance of reaching the ADC or anyone squishy enough for him to kill before needing to ult.
The meta for the last few patches since the devourer buff was assassin meta, so you'll see a lot of supports that peel exceptionally well and make your life harder. But it should be shifting back to tank with this patch, so you should be fine to use tryn again as soon as 5.18 is fully implemented (they still haven't done it yet I believe)