He also had injuries during most of the previous seasons. In 2008 he couldn’t compete until late June due to a severe pec tear, yet ran 9.72 two months later. In 2009 he was sidelined by injury until late May and only reached a SB of 9.82. His 400m times before 2009 do not compare at all to the 2009 PB (45.94 in 2009 vs. his previous PB of 47.17 from 2007). If a significant 400m PB for a 100/200 sprinter is due to improved speed (and thus a better speed reserve) you can expect good performances from them over the rest of the season. If it is due to an increased focus on overdistance work, intensive tempo, etc., however, it may actually be detrimental to performances over shorter distances.