Let me answer your question with more questions? Why do you think the NCAA limits the amount of practice time that teams can have in the spring, summer, and fall? Do you think that teams would be better if they had more time together? If so, what happens when the guy who is your best prospect at Center is only a Redshirt-Freshman, and he's missed most of the practices in his first fall on campus, some of the practices in his first spring (he wasn't an early enrollee in 2018), and he missed all of fall camp except for the last handful of practices? Do O-linemen get better when they get a lot of practice time together? What would you expect from them if they don't? What if there is no Option B that's better?
That's where the O-line is. Even if he had taken every snap in the spring and in fall camp, Jurgens would have had a steep hill to climb as a Redshirt-Freshman starting at Center after having never played the position before at any level. The fact that there was/is nobody older than he and Will Farniok to start, right now, shows the lack of depth that Frost inherited.
It's basically the same story with WR, except it's more people involved. WRs and the QB need to practice together as much as possible, and that includes 7-on-7 in the summers in addition to spring football and fall camp. Two of the WRs who were expected to hold down the X-WR position haven't been playing: Hunt got kicked off the team the week before the first game, and Woodyard has been hurt. The Swiss Army Knife guy who organized all of the practices all summer and who knows how to play every WR position--Kade Warner--has also been out with an injury. The guy who has been filling in--Kanawei Noa--is a summer transfer from Cal who had to learn the offense over the summer without the help of the coaches. Even NFL teams wouldn't look good in those situations. If the WRs aren't doing what Martinez is expecting them to do--and it doesn't even matter which one is right or wrong--you're going to end up seeing what we've been seeing: a lot of QB sacks due to the QB holding onto the ball too long because nobody came open. Even Tom Brady couldn't be successful in that scenario. In fact, that's pretty similar to the situations in the past decade or so when he's looked horrible: a veteran WR leaves the team, another is injured, and it takes awhile for the newbies to get on the same page with him.
If you're saying that you hope that the team looks better at the start of the year than they have this year or last, yeah, I'd say that Frost and everyone else is expecting that also. If you're saying that you're expecting the team to play error-free, veteran football at the start of the year, you're expecting too much. Even Nick Saban and Dabo Swinney will tell you that their teams look like crap in August as compared to what they look like in the first week of December; why? The gametime experience matters, and it can't be perfectly replicated. Some things just have to be learned by going through them in games.