Does anybody know of a website that can let you know when an external link was created to a site? Or any other way of finding this info out. Thanks

I was wondering if anybody can shed some light on any recent changes to the Google algorithm in Australia. A competitor, www.manwithavan.com.au has always been number 1 for the most competitive search term in our industry "removalists melbourne". However, in the last week, they have fallen out of the the SERPS and are now (according to MOZ) ranking outside the top 50. As far as l can tell, they have a really well optimized site with good structure, great text and updated content. They are very active within social media circles and have some really good external links. Can anybody tell me why they would have been hit so badly. The reason l ask is that i want to make sure we don't make the same mistake. Any feedback would be greatly appreciated.