Not necessarily.. The guy is clearly impressive but he is 1-0 at Welterweight and his biggest win is over Gerald Meerschart who has a UFC record of 6-6.
There are other guys at 170 who have better records over higher ranked people who are not in the top 15. The ONLY reason Chimaev is in the top 15 is because he has a TON of hype behind him. Dont get me wrong, the hype is justified but that doesn't mean he should be in the top 15 at only 1-0 in the division by beating someone who doesn't even have a win in the UFC...
Khamzat is 3-0 in the UFC but his opponents have a combined UFC record of 7-13. That does not warrant a #15 beside your name.