The thing about Olcay is.. he scores some amazingly beautifull goals but at the same time he also misses one on one quite frequently (luckily not against Fenerbahçe in 90+3 :p). His shot accuracy should definatly be in the mid 70's though if you ask me.
As for assists.. he's not really the type of player that gives a lot of assists, he gets on the end of throughballs more often and gets in scoring positions but he rarely makes great crosses or anything like that.
I'd say his main strengths are his reaction and stamina, he works hard and is running the entire game.
His pace however is quite overrated in this set, I wouldn't put him as high as 88. Maybe 86.. and even that seems steep. However I'd put his SA on 75-76 and his reaction 76-78. Stamina can easily be 90. If you look at his goal against Fenerbahçe, he got from our box to their box in 13 seconds in the 93rd minute and he is pretty consistant in his tenacity throughout last season.
Here's a video, you can see his goals. Pretty much all of them are beauties but take my word on it that he also misses quite a few chances. He coudl've easily scored 20 goals last season with the positions he gets himself in to.https://www.youtube.com/watch?v=cRfufMUyvVI
Don't be mistaken, he's an incredibly usefull player but he also tends to be 'invisible' for large portions of our games.