I have been able to get the flight as low as 8000 points but it’s not the norm. It’s usually about 25,000 and higher in some time frames. They will divert if the runway is wet and if the delay in SJU is to long they will bring the flight back to MIA rather than stranded the crew and aircraft in Tortola. 90% of the time however they are able to grab fuel and get back to EIS if they divert.