Hi, sorry to see those results

The deck seemed way faster, of course you won't be always ready for a T3 kill, but there are some pairings that should be favourable.
Why did you lose "long" matches? was it because counterspells (gsz, specially)? spot removal? mass removal?
I really think that gsz is a liability. Yes, it's a super tutor, but it gets countered lots of times and cavern does not help, and sometimes the extra mana is relevant, specially under thorns.
Another craterhoof could work wonders! probably you lost some matches waiting for it, or having gsz countered. Or maybe not, so that's up to your experience

Symbiote+visionary is great in long matches, but if you seek to win quickly (and you should, with all that acceleration), i'd choose another drawing engine, more explosive. Maybe glimpse, maybe call//beck... call//beck is specially interesting since it works with hivemaster tokens, getting really broken once you have both online. of course that version needs tropicals, and I wasn't really happy when I goldfished, but ancestral and time walk would also be really valuable.
Thanks for sharing your results!