The unemployment rate in Indiana has indeed dropped steadily since 2013 — but the trend began before then. In fact, far from being "very unusual," Indiana's change in employment is pretty squarely in line with the rest of the United States.
If we map the state's unemployment to the country's, you can see how the two have risen and fallen in remarkable sync. Indiana's was higher than the country as a whole in 2010, in the wake of the Great Recession. But when Pence took office, it was only a little higher.
We can see the comparison more easily by looking at the change in the unemployment rate over time. Relative to the unemployment rate in January 2013, Indiana's unemployment and the country's have been very similar. Under Pence, the rate did fall slightly faster than the national rate — until an uptick in recent months. Trump praised the Indiana unemployment rate in May of this year, but that rate was slightly higher (5 percent) than it was last September (4.5 percent), according to the Federal Reserve.
The change in the state's rate of employment is similar to the national change. The country as a whole has added a lot more jobs simply because it's bigger, but the country has added jobs at a slightly higher rate than Indiana, relative to when Pence took office.
Over the past year, there is no state where unemployment is down anywhere close to 40 percent. In only six states is employment down, including North Dakota and Wyoming (hurt in part by the oil market turmoil) where employment was down about 3 percent. Indiana's employment was up 1.3 percent over the past year; the national median for states was 1.3 percent.
Unemployment declines are good. Employment is good. Indiana, in these regards, is not remarkable.