Tempo run

Yesterday was so slow and easy. So today was fast and hard. I wanted to do 1 mile warmup, 2 miles tempo and finish with 1 mile cool down. I started the tempo a little too hard and only did 1.5 miles. But I was able to slow down and run the final 1.5 for cooldown.  All told, a tough workout.  I'm going to be sore tomorrow.  Here's my splits:  Warmup, 9:06; 6:54; half, 3:30; half, 4:36; half, 4:43; half, 4:45.
I just checked the training calculator on RunnersWorld.com.  According to my 5K finish time, I should run my tempo runs at 7:31, not 7:00 like I did.  Maximum oxygen at 6:47.  I need to work on my pacing.