Starwalker was roaming around in his Tristan and saw four T1 frigates in a medium complex and immediately recognised Semirande as he had only recently destroyed his Atron. The default assumption was that all four frigates were together and a quick check of local revealed a number of people in the same corporation as Semirande.
Starwalker thought it was very unlikely that he could take on four frigates at once but he also wondered if the four were perhaps actually doing the complex and if so there was a chance to engage just one or two. It would be a risky choice to go in as it was equally possible that they wanted to catch something entering the complex. Indeed retrospectively he saw that they had killed a Thorax only 15 minutes before.
Whether it was courage or stupidity Starwalker decided to give it a try - no guts no glory. He warped into the complex and was met by all four frigates as he entered, they were waiting for the chance to pounce. Starwalker went for the nearest ship, the Rifter, and launched his drones. However, momentum changed the relative positions and it ended up 7km away with the Merlin and Republic Fleet Firetail being closer.
The majority of damage was from the drones but this early targeting had the effect of splitting the Tristan firepower because the blasters were out of range. Worse, the drones did not all go after the Rifter and the log showed that they seemed to split their attention between the Rifter and Firetail. Normally Starwalker set the drones to focus fire to concentrate their fire but perhaps Starwalker had switched to the closer Merlin and Firetail.
In any case, the Tristan was taking a lot of damage and was not doing enough damage in return. Given that, it was inevitable that the Tristan would succumb quickly and it did so. There was an Incursus there as well but that must have been out of range when Starwalker arrived as only the other three frigates were on the killmail.
When Starwalker reconsidered the fight he realised that he should have thought about the fight before entering the complex. To decide what he would do if they were waiting for him. Given this was a trap, his only real chance was to overheat his afternurner and speed off away from the frigates rather than engage directly. That manoeuvre was not intended to run away but to split the enemy targets. If he was able to inflict heavy damage whilst avoiding as much incoming damage as possible then he had a chance. Brawling against the odds was not a winning tactic.