A lot, and I mean A LOT of midlane players these days seem to have the same problem – they get stomped mid, and the match proceeds to only go downhill from there. Now, is the opponent really a smurf, or maybe just a player having a good day, or maybe just a natural counter to your hero? It doesn't matter, because this tip will work against all three:
Change your lane approach as soon as you start to feel the disadvantage
If you keep getting your last hits messed with, if you die once or twice, or if you're scared to approach the wave too closely — respect the opponents skills, and change the way you lane. This can be several things:
For flash farming heroes, prioritise jungle over lane. Only come to the wave when it's safe under the tower or the opponent does a waveclear and leaves.
For level 6 powerspike heroes who cannot jungle effectively, start converting your lane farm into regen, just so you can keep laning until you hit that powerspike, then make plays in the sidelanes.
For everything else, a mix between the first two options.
After some time the enemy might start threatening the tower – do not worry, just let a support take over the lane, or just let him hang out nearby, responding to possible dives and helping with rune control. A lot of enemies become overconfident and can feed in the 2v1 scenario. And even if supports are busy or the enemy can push 2v1, it's better to give away the tower than to proceed to hang around the lane and risk dying.
Now, you might be wondering — doesn't this give the other dude a free lane? Yes it does. But what's better, a free lane of creeps, or a free lane with hero kills and a tower? Smurfs or not, players rely on snowballing to take over the match. If you take away their ability to feed on you, they will have to either look for another source such as jungle, or the sides, in which case it's either space, or a possible response opportunity.
So, to recap – if you feel like you can no longer play in the midlane, then do not play in the midlane.
This topic brought to you by a non-smurf Immortal Storm main, whose opponents often do not recognise when the lane becomes a kill lane for me, and it takes them one to three deaths to finally abandon the lane or station a support.