Tempo Run for 4 miles

Warm up for 2 miles. 4 miles easy tempo run.
It rained last night, there was only a few puddles.
But overall condition was ok.
Then cool down for one mile. Not everyday is a good
day for fast running. Just felt like could not run faster:

Split	Time	Distance	Avg Pace
Summary	1:00:25.0	7.01	8:37
1	9:01.2	1.00	9:01
2	8:12.2	1.00	8:12
3	7:50.5	1.00	7:51
4	7:45.9	1.00	7:46
5	7:58.1	1.00	7:58
6	8:01.5	1.00	8:02
7	9:00.5	1.00	9:01
8	:05.3	0.01	8:37