Everything else being equal I could also see going with Holtby over Mrazek for a couple seasons, but I don't see that as being a realistic choice. Mrazek is signed short term at $3.125m per. Holtby is going to want term and a lot more money than that, and both would be too risky and wouldn't fit into the Cane's organizational philosophy, imo. [btw, I'd rather not go into next season with Mrazek in goal unless it's as a 1B and we add a 1A who's even stronger]
We'll see how the league values Holtby, but I'm thinking a reasonable analogy might be Eric Staal when his contract with the Canes ran out. An aging star whose recent performance lagged well behind his career highs, seems like Staal was basing his value on his total career, while the Canes were basing it on recent performance. Turns out the league felt the same way as the Canes, and Staal went from an $8.25 AAV contract to $3.5m on the open market. I'm guessing Staal could have re-signed with the Canes for more than that had he taken their best offer. Not saying Holtby will fall quite that much, and I hope that his negotiations with the Caps are amicable, so that staying with the Caps remains an option if the market doesn't value him as much as he might anticipate.