Doesn't seem like small club tactics to me..
I didn't really think Celtic played "little club tactics".
Overall, I thought Celtic were very well-coached and prepared in what they tried to do (aside, I suppose, from the obvious fact that plays into Juve's strength to press them). Celtic just have nowhere near the quality Juve does anywhere on the pitch.
In fact, that Celtic came out guns ablazin' and trying to press Juve deep led to the early goal and that they never really dropped everyone deep in their own area is more why they lost 3-0 and risked even worse.
I'd also defend that Celtic CB that made the two mistakes. The two errors were certainly costly but it may have been more the "law of averages" considering the quality of Juve's counters.
Otherwise, he did a very sound job keeping Vucinic from holding up possession and spraying his usual deadly passes to all the midfield runners or back to Pirlo in space. I've seen Juve quite a bit this year and many respected CBs have fared a lot worse. I'm sure his more imposing physical/athletic play was why he was chosen.
Celtic deserves credit for risking an home thrashing on such a big stage by not going into a complete shell and facilitating what I found to be a pretty exciting match.
If there's any criticism as far as "small team tactics," it's that Celtic's degree of simulation, from begging for cards and free kicks over clean tackles to the little extra kicks on Pirlo seemed more befitting the script of Central American WC qualifiers at times.